Just in case someone is still confused. In the beginning I say how peak velocity is 75 but then show a graph where it's at 90. To understand this you have to keep watching because at 08:45 it's made clear how 75 is with the rod, 90 without the rod. When we speak of primary balance alone we imagine that the piston magically moves up and down, we pretend it's a free piston because we are isolating it from the rod to observe its forces. When we add the rod we get the total. In the beginning I speak of the total and then about the primary, but I don't think I stressed this properly so maybe that's why a few people got confused? Support the channel by shopping through this link: amzn.to/3RIqU0u Patreon: www.patreon.com/d4a Become a member: th-cam.com/channels/wosUnVH6AINmxtqkNJ3Fbg.htmljoin Fortnine's video: th-cam.com/video/Qn9JrN1JERI/w-d-xo.htmlsi=ugzeqkMabvfo9h2f
Thank you, this was all very interesting material. I always thought that the largest source of secondary vibration came form the counterbalance weights on the crankshaft. These are rotational, and so cannot do more than a "passable" job of counteracting the reciprocating and rocking forces. That is what I had always read when I was young. This balance weight was supposed to approximate the piston weight, plus a part of the conrod weight. There can to be only a "reasonable" balance applied for all the reasons you point out about how pistons and conrods generate their forces; but mainly because at ~90 degrees that counter weight is creating a sideways force. I have seen illustrations of patents for engines using two crankshafts and conrods per cylinder to counter these half-stroke forces. The most commonly expressed way to balance the piston weight without balance shafts is the use a 90-degree V-twin with ~100% balance weight on the crankshaft - the half stroke forces from the piston tending to balance against the second cylinder's piston. As the two cylinders usually share the crankpin, the rocking couple is also small. In reality you can never fully compensate for *all* the out-of balance rotational and linear forces. If my memory serves me well, there are a few other really minor things in your presentation that were a tiny bit in error. I am reasonably sure that there was an mid-'70s Yamaha 500cc 2-stroke single motocross bike that used a balance shaft - and probably needed it! This was not at all a common bike, but when I was buying my TY250 I saw the ads for it, and thought it's technology was interesting. I recall it had only 4 speeds in the gearbox; presumably to fit more robust gears into the narrow crankcase? The other comment you made concerned the use of "big bang" technology, before the idea made it to the MotoGP "big bang" 4-cylinder 2-strokes. But the advantage of "long" pauses between the firing impulses was known in British big singles. I read about it in a UK magazine about a decade before those 2-strokes, in reference to a BSA 441 that had been turned into a road racer. It was noted as losing out badly to multi-cylinder 500s on the straights, but having better traction on the corners due to the relatively low revs and relatively large flywheels leading to the tyre still driving the bike between the impulses, and remaining in non-slip contact. Combining slow-revs with big flywheels to drive through areas of poor grip was exploited widely in Observed Trials. Modern Trials bikes have taken a very different direction.
You are wrong!!!! Just giving you wanted to see in the comments! 🤪 Thank you for your explanations of mechanics (physics?) in all your videos. Teachers should strive to be as clear as you are..
An intelligent and thoughtful man respectfully and succinctly peer-reviewing another intelligent man's work, all while acknowledging the FortNine channel's brilliance and success. This is A+ content.
As a fortnine viewer, this should be interesting. EDIT: The respect you show to him as a viewer and also a creator in a similar space is NOT TO BE UNDERMINED. Its so different than just going at each others throats. You two are awesome!
Yeah. I quit watching him years ago after so many mistakes and pushing his opinions as fact. He's a hipster rich kid who knows a few things, enough to sound like an expert but far from being one.
@@VndNvwYvvSvv Ryan is a salesman. Ever since the channel took off I did notice a hint of ego in each of his videos. In the end, he's really just a salesman and fellow rider.
@@Kevimoto He has been a social media influencer for all of his professional life. A bachelor's degree from 10 years ago is a helpful starting place for knowing how to think about science, but it doesn't give him any usable expertise. He is a very intelligent and knowledgeable person, but his profession is content-creator, entertainer, and marketing professional, not educator, journalist, scientist, or investigator as some of FortNine's content portrays him.
I know I know I know what Ryan is! Pick me! He's a person. A person that obviously works hard to entertain and inform you. I prefer to enjoy and appreciate what someone does rather than try to pin subjective labels onto their personalities or careers in an attempt to somehow minimize their achievements and make me feel better about myself.
As a fellow who has been described on more than one occasion as a sandwich short of a picnic, I agree. If someone can knock knowledge into me, they can drive a thumb tac into a brick with a broken finger. This guy is good.
... though I'd have loved to have seen the overall imbalance graphs with the easily-counteracted primary vibration subtracted, to see what is left over.
Yeah, I did think the 285° thing sounded a bit off from previous videos and research I had seen about engine balance and crossplane engines, but I didn't have the time to check F9's work, so I'm glad you did. As far as the forging goes, yes it is cheaper and easier to make a 270° crank than a 285° crank. When forging a 270° crank, you can set up the 2 halves of the forging dies so that you forge in one journal then turn the crank 90° or 270° and forge in the second journal without affecting the first journal. Due to how the two forging dies come together, you can't really do that if the journals aren't either parallel or perpendicular to each other. Thus, for a 285° crank you would first forge in the journals for a 270° crank, then use a separate machine to twist the crank that additional 15°. Since this requires a completely separate machine along with an extra step, most companies just stop at forging in the 270° crank.
Hi r.j.bedore9884. You seem like you are very confident in your statements re: twisting of the 285 degree crank after forging. I'll be honest, both these guys seems to have a much better grasp on this than me... although I understand the math, but not the manufacturing process. I am just wondering where your confidence comes from? Are you someone who actually has some experience in this field? It certainly seems so... I'd be curious to know. Thanks! :)
@@steveblackwood1202 I have some experience with creating forging dies while getting my engineering degree in college, but I will admit I haven't forged a crankshaft myself. This is just what I remember the guy heading our machining lab telling us when one of the guys in class asked about making a new crankshaft for an old motorcycle he was restoring and having trouble finding parts for (this was back in 2006/2007 before buying parts online was as easy as it is today). Because forging generally involves smashing two large plates together with the shape you want carved into them, you tend to have trouble making dies that would let you have angles that aren't either perpendicular or parallel to the direction the forging press is moving in. For crankshafts whose journals aren't either all in one plane or perpendicular, you can either forge a blank then twist it, forge multiple pieces then spline or bolt them together at the correct angles, or machine the entire thing from one large billet of material. Making the forging dies can be expensive, but making the parts with them is faster and cheaper than the other methods, which is why most mass produced parts are made this way, and why most parallel twin bikes have a 180° or 360° crankshaft since that is easiest to forge. Machining a part from a billet is more expensive per part, but if you are only making a few for a prototype, or say for a race engine, this is almost always cheaper than getting a custom forged part. Hope this helps.
@@seth094978 No, while 270° crankshafts are becoming more popular, many are still 180° or 360° like the Kawasaki Ninja 300/400, Versys 300/400/650, and W800, the Honda CB500 series of bikes and a few others, several BMW parallel twins, some Royal Enfield bikes, and until recently nearly every Triumph parallel twin was a 360° crank. I think there might have been some Yamaha cruisers in there as well, but I'm not super familiar with those, and I'm not sure about Suzuki since I'm mostly familiar with their V-twins. Also, I believe the motor in the RS660 and its sister bikes is the only Aprilia parallel twin with a 270° crankshaft. Thanks to the popularity of the Yamaha MT-07 and KTM 790/890 bikes, crossplane crankshaft twins are certainly on the rise, but they haven't taken over the market yet.
This would be awesome indeed! I would imagine both of these guys having a thoughtful discussion about this topic, and then having a few laughs about plenty of other things. Could make for a terrific live podcast type of interaction.
as a mechanical engineering student who has done a semester long project developing a MATLAB model simulating exactly what is discussed in this video (acceleration and force modelling, advanced kinematics and kinetics of mechanisms) i have to say your style of lecturing is WORLD CLASS, you never lost me once during this video and I imagine even someone who has never taken high school physics can follow along the fundamental concepts explained in this video, even though you make no sacrifices in justifying your claims. Well done!
Not saying the video wasn't good, because it was. But "not losing a mechanical engineering student that did a semester long project in exactly what's discussed in the video sounds like " sounds like the absolute bare minimum no?
No, not really. It differs from person to person, but especially in mechanical engineering, sometimes you get a professor that does not do a good job explaining complex topics, so you can get lost pretty quickly. I think what he meant was that even with his knowledge on this, it was easy to follow, simplifying it enough that it is digestible for most people. One can also get lost when someone is explaining a topic that you already know. I remember once that a classmate of mine explained smt in thermodynamics that I already was familiar, it was just the way that he explained it that got me confused and lost. @@AirSKWolf
As someone that wanted to study mechanical engineering and chenged my mind, oh Man, 6 months doing a project in MatLab, I chose my career correctly 😂😂😂 just kidding, I don't have enough patience to do that kind of work.
I'm a machinist who works with fixtures and dies, and I have a lot of manufacturing experience. I came to the same conclusion you did about the manufacturing process after watching Fortnine's video. While I may not have much experience in an engine manufacturing plant (very little and none relevant to the question at hand), It seems to me that creating a die and platen that can stamp out a 270 crank would mean that you could do the same for a 285 crank just as easily. From my experience, the time and cost difference to make the tooling would be negligible. Again, I have no experience with heavy forging like what you would need to create a crankshaft, but I'm having a hard time believing that it would take any extra steps to create a 285 crank vs a 270. Even the finishing machine work would be very similar.
Just want to say much respect to you brotha ... my grandfather was a tool and die maker and that is a dying art so I say much love and respect to you my friend and thanks for the good memories you reminded me of when my pepeir was still alive and well and owned his own land and such he had a big red barn (go figure right all old barns lol)and it was full of nothing but machinist tools , giant lathes, mills , presses and all kinda shit I still don't know but they were so cool and all done by hand and man did he make some cool stuff ... rip to him but man if he was in his prime doing that as I am building cars now , me and him could made some super radical 1 off parts for mooorrrreee powa baybay 😅 lol ... peace and love bro keep it rad stay safe and build on l8z fam and much respect to you friend
If it's a 3 journal crank you could even use the same forging dies; just take a freshly forged, glowing hot 270° crank and twist it ever so slightly to make a 285° one. It's an established process on crankshafts for engines with more cylinders- th-cam.com/video/mj8leWsB4w4/w-d-xo.html
Tooling is tooling. It would be more expensive to retool for 285° or whatever other offset you want than to continue to produce whatever you are already producing. If you are starting from scratch, you're going to be tooling for whatever it is you want to produce, it will be no more or less expensive to set up for 270°, 285°, or 180°.
Hello, I share your opinion @operator0 but I think that adding an 15° angle to the die would add transverse forces that would not help the two parts of the die align well (could still be achieved??) ... But I am still a student in this domain so take it with the biggest pinch of salt.
@@kender1412 That's the exact same reason that Boeing still makes the nose of their 737 the same, even though more efficient shapes have been found. "Tooling is tooling," and reshaping would require different tooling, so the legacy shape remains.
wow. a professional and respectful critism to my favourite motorcycle channel. I no longer have a favourite motorcycle channel anymore, from now I have 2. :) thank you very much for taking your time and correcting their mistake. Please consider collaborating with them in their future engineering related content. now if you excuse me I'll be binging your videos :D
Thank you. That's the attitude I really hope to see after this video. I really don't want this video to take away from the amazing content f9 produces. As I said this really is a complex topic and all the other points in their video are excellent
@@d4aGreat video as usual! I would love to see your take on some more motorcycle engines, potentially comparing v-twins? Ducati vs Moto Guzzi vs Harley vs Indian etc would be pretty cool, maybe too many for one video though!
@@d4a wow thanks for the reply, I'm glad you like the idea! A video on desmo valvetrain alone would probably be a lot, and then maybe euro v-twins could be one, and American v-twins as another... Just thinking out loud. Lots to cover but whatever you end up doing I'm sure it'll be great. Thanks for all the content!
Nice! Two of my favorite youtubers in constructive and respectful debate! This is so insanely wholesome compared to the usual primitive beef amongst communities. My inner scientist is happy
It is always said that the main reason the KTM LC8c parallel twin has a 285 degree offset is to mimic the feeling of the bigger KTM LC8 V-twin engine which has a 75 degree opening of the V. And thank you for this explanation, it was great!
Yeah, this is the reason I first heard as well. Though I admit that I liked F9s interpretation because it “elevated” my 790 into a special premium category that could have been used for a few extra bucks on resale. But not anymore. Damn.
After some research, I found exactly the same, but on a BMW f800gs, crank is 180, but the firing is 360 due to the layout and in result it will mimic the sound of the R1200gs (that rich sound of the boxers)
@@steamixion (I did before watching the video, but tks anyway) I can't stand the vibration in my 800GS, really annoys me, looking for a V twin now. (probably a Vstrom 1050de)
Phil Irving's original driver for proposing 76 degree crankpin stagger (referred to here as 285 degree), was to use the maximum inertia of one piston to help the other over TDC; in other words, to reduce the size and weight of flywheel required for low-rpm running. He was grappling with the need for more flywheel effect on the AJS Porcupine, and had vast experience of the assistance of one piston for another on V-twins. As the presenter here notes, crankpins at 360 degrees, 270 degrees and 285 degrees are all have their advantages. All can be fully balanced with balance shafts, but 285 degrees maximises the free flywheel effect. By the way, Irving's 76 degrees (effectively 284 degrees) was based on conrod to stroke length ratio of 2:1 - common at the time.
The 285 degree parallel twin most commonly mimics KTMs 75 degree V-twin. Turns out it is a KTM brand character thing and nothing else. Great presentation!
As 270° is imitating a 90° V twin. And the forgotten Husqvarna nuda 900 (italian engineered high-bored f800) has 315° crankshaft, mimicking the 45° V twin (Harleys).
This is the correct answer. And lets not forget, parallel twins are just the cheaper to make alternative to the real v-twin as you only need one cylinder case and half the camshafts. And you also get rid of the cooling issues of the back cylinder.
As someone who does not have any background in any types of engineering, I found this video and explanation to be extremely enlightening. If you can bring Normie’s along for the ride in such a way, I think you’re both winning.
I am one of those 50% so I will correct you :D TL:DR The reason KTM went with the 285 is experience. What once used to be a necessity for creating a compact V-Twin has helped KTM in creating a well performing Inline 2 without having to start from scratch Back then KTM only made single-cylinder bikes. The idea for a KTM two cylinder idea came from a university student project; a V-Twin made from two KTM dirt bike singles. The students didn't want to use a 90° cylinder angle because the engine would be too long. So they decided to move the cylinders closer in a 75° arrangement with a multipurpose shaft between the two cylinders which balances the engine and drives the water and oil pump aswell as the the alternator. Shortly after Pierer started developing the LC8 (Liquid Cooled 8-Valve) The basic arrangement stayed until today. KTM spent more than a decade on perfecting the 285° V-Twin so when they wanted to join the midpriced segment they designed the engine in a way that they can use their knowledge from LC8 development to make the LC8c. (c for compact)
Awesome to see a video response from you to the F9 video. To me the only thing that felt weird originally watching the F9 video was your last point on the production of the crankshaft. Instinctively it feels there shouldn't be a difference. Yamaha for example also makes the CP3 engine with 120° between cylinders so it's not like Yamaha can only do variations on 90° affordably.
Your physics are spot on and so are your conclusions. A couple of minor points. (1) the angle of the peak velocity can be different depending on the length of the connecting rod relative to the stroke. The specific equation can readily be developed with a little trigonometry, it can also be found in Taylor and other engine textbooks. (2) a primary method to reduce the first order vibration are the counterbalances on the crankshaft itself. Now open the Pandora box on balance opposed (e.g. Boxer) engines. Perhaps an upcoming video of yours
IDK if he ever mentioned what you said in point 1, but I know that many times he mentioned what you said in point 2. Just not in this one. I'm almost certain he did cover boxer engines, but it could have been in the video about something else. I would have to check.
Excellent point about the variable nature of the secondary imbalance with rod length. Ideally we would use rods of infinite length, but there are packaging issues...
This is how someone who knows what they're talking about proof reads someone else's work. Beautifully done! So nice to not click a video and listen to bitching and snide comments, just eloquent facts and research. Love the channel dude, cheers!
One of my favourite bikes ever was my 1998 Yamaha TRX850, a splendid machine that was the first (mass market) 270 degree parallel twin to hit the streets.
An old acquaintance of mine owned one of those when they were brand new. He loved it, and I was in awe of it. On paper, they appeared to be a fairly "middle market" machine. He was the first to admit that top speed wasn't its strong point, but in the "real world", he could round up just about anything on that bike. And when I say "real world", I mean on the track at ride days, as well. Yes, CBR 900's would have him on the straights, but at the end of a lap, there was nothing between them. And on the road, nothing could keep up with him, and he wasn't riding like a lunatic, the bike just did it's "thing" with ease. I would have loved to have ridden it but never got a chance. l don't know why I own a Kwaka. I'm a huge fan of Yamaha.
@@davidbrayshaw3529I had 3 .... Did plenty of trackdays on them ... The genius of them is they made you look much better than you actually were.... Only negative was a gearbox like a bag of bolts....
@@stevebayross7248 I wasn't aware of the gearbox issues. That's very un-Yamaha like. You're pretty much echoing the words that my acquaintance said. I always thought that they were a fantastic looking bike, too. Great note, to boot.
I worked at a dealership when the 'Super Tenere' XT 750 came out. That was in late 80's. Yamaha barely mentioned the crank design. A 137mph trail-bike was totally crazy (I did one of the very first modified carb / air-box / exhaust ones)
@@davidbrayshaw3529 the Yamaha gearbox is almost always terrible the first year, usually second gear breaks' Always gets fixed second year with stronger parts that retrofit early models. That was my experience at dealers until I left in 1990
I had issues with Fortnines claim. I do however rarely comment on anything. So this is one of those rare occasions! 😅 Keep up the good work. As a certified gear head your channel is one of my favorites. 👌
He says a lot of things that aren't true. Especially when it comes to what gear or parts are best. He has enough shallow knowledge to pretend to be an expert.
Very few channels write their content scripts with such quality, mechanical accessibility, and wit like FortNine. So many wonderful lines semi-hidden in the presentation. One of my favorites, "it's said that every time a CBX hits redline a mechanic finds his 10mm."
yep. In an older video they used unscientific tests on some gear (was it helmets? oil? both?). I pointed out the issues in a comment but they were not addressed. Love their story telling, but I won't trust their tests
Lol I commented on that video yesterday - "I can't wait for D4A to take this on!" =D The KTM doing 285 cranks is similar to how OMEGA has co-axial escapements, it's essentially marketing.
Yup, the 285 crank exists for the same reason as the 270 crank became popular after the MT-07 (though it obviously existed long before that). It's marketing the exhaust noise and engine "feel", imitating that of a 90 degree V-twin. There's no actual real world performance benefits to this setup over a 180 degree twin, if anything the 270/285 need balance shafts where the 180 doesn't. But the 180 sounds flat and has a lumpy feel. The 270 degree crank is being widely used because customers liked the sound and feel of Italian 90 degree V-twins in the middle weight, with the parallel twin being vastly more economical to produce and fit in a smaller frame/overall wheelbase.
Except d4a's graphs are all wrong making this entire video incorrect. If the piston reaches max velocity at 75 degrees, it's force will cross zero at 75 degrees. The wave is squished at the top, it's not equal top and bottom.
I’m a huge fan of d4 and fort - my only favs. I am so grateful that d4 pushes me/its audience more than fort in grasping the more difficult. I love it when my brain hurts.
This is great! And the TH-cam algorithms worked great, too, since I just watched F9's video on this yesterday. You sir, are truly a top level teacher!! 👍🏼👍🏼
Čestitka za milijun subscribera!!! Videi su ti za svaku pohvalu, uvijek nam preneseš puno znanja na jednostavan način i hvala ti na tome što obrazuješ ljude širom svijeta!!! Pratim te dugo vremena i srce mi je puno kad vidim ljude iz regije kako uspijevaju na youtube-u, ali mi je pogotovo drago zbog tebe jer daješ inspiraciju i meni i drugima da se bavimo automobilizmom i mehanikom. Lijepi pozdrav za tebe i tvoju obitelj, neka vas Bog čuva i sve najbolje u budućem radu!
Prvi put vidim ovaj kanal i odma mi je palo na pamet da covjek izgleda kao Srbin. Nista nacionalisticki nego me bas zanima da li sam pogodio, jer po lajku komentara ocigledno jeste balkanac 😂. Pozdrav iz CG
Finally an actual analysis and explanation. Fortnine makes great content, but as an engineer, it frustrates me how he gets the reasons wrong for many things. He explains things beautifully, but I believe he misunderstands fundamentals of why engineers make certain decisions. Same thing with his materials video.
At 18:37 the 5-cylinder crank fairly clearly has the pins at the correct angles; no.3 is horizontal, 2&4 are 144deg out (furthest from the centreline), and 1&5 are closer to the centreline. Unless there's some weird overhangs on the crank I don't think there's any reason to twist it, the forging dies can be made to the final crank pin positions without a problem, just anything other than flat-plane needs more complex dies with deeper (more difficult/expensive) machining. The only time I've heard of twisting a crank was one of Audi's DTM engines, turning a cross-plane V8 production crank into a flat-plane V8 for racing, and I'm not sure I believe that other than as a justification for skirting the rules.
i respect this guy. i remember he debated about brakes and even some engineer ( as they claim ) were wrong and i agree what he said. sometimes someone who has higher education or a degree may be wrong . just like Veritasium who did a debated about acceleration of energy can move faster than what energy it has. thats the beauty of science though. you debate and prove each other wrong and the accept it as when they been proven wrong. thats how science becomes more accurate because when its proven wrong or right it added the level of extented experiment to validate.
@@LeoNidasPlayForFunmake it use 7 valves, too, with one that doesnt connect to anything but has a deep well behind it, just to add complexity and keep the mechanics on their toes
@@Fightre_Flighte True, maybe make the air intake have a second, smaller filter right before its output as well, and require a special tool to service it.
You are the BEST, my man, at explaining these types of mechanical issues!! Your graphics and explainations are superior to any others I have come across on YT, or anywhere else for that matter! Kudos to you... especially since English is not your "native" language! BRILLIANT WORK!! 👍
I also got a bit shocked by the better 285 better balance affirmaton on fortnine's video. Thanks for analysing that fact. At least I completly agree with the polution reason for the return to that configuration nowadays,
@@tedarcher9120 They don't really have worse balance but they also don't have better one. Also, I doubt they're significantly harder to produce. It's all in the video.
@@snapcountersteer I was going to say this if someone else hadn't already. Why KTM's LC8 V-twins have run 75° instead of the more common Ducati style at 90°, I'm not really sure. Packaging a Vtwin with a wide angle is a problem in bikes. V-twin engine are already expensive to manufacture and make everything else more complex (cooling, intake, throttle body packaging, airbox, exhaust routing, transmission placement, camshaft actuation, and a lot more). I think the crowd who loves to criticize the lowly "parallel twin" engine configuration does so on the basis of having an emotional connection to V-twins, which of themselves, are sort of a historical rebellion against the trend of inline-4's. I'm not really sure even the Vtwin folks who criticize parallel twins understand why they have the emotional reaction they do. Sound signatures between a Ducati and a CP2 Yamaha are nearly identical. Close enough to be hard to distinguish. Certainly the vibration and sound between the two configurations is not identical as a Vtwin lopes and bucks irregularly while idling, and the Parallel twin tends to have various RPM where buzz appears and disappears, in my experience, the Vtwin stays pretty much the same vibration at all RPM ranges.
Thank you for this incredible video. Upon watching the F9 video, I was annoyed because I couldn't find anything substantiating their claims and honestly couldn't make sense of it because my last lecture on engine balance is a few years back. Something about their simple geometrical explanation irked me, and you explained how it actually works so freaking well. Fantastic stuff.
Thank you. I was wondering about the claim that manufacturing the 285 is more difficult. It didnt sound quite right. But you went even farther to analyze the secondary balance forces. Very insightful. I am not a mathematician but there has to be a formula to calculate the crankshaft offset to achieve minimal secondary balance on a parallel twin.
Love your video's. I sometimes struggle with English as a second language accents, but you come through clear as a bell! The graphics are excellent. They are simple and not cluttered, and perfectly illustrate the subjects.
@@Fightre_Flighte I mean not really, cause if D4A calling you out means you have to have some idea what you're doing, where McNally abusing your lock probably means you're masterlock and that doesn't *really* have the same implication.
13:49 The Rotax 652 single cylinder engine in my motorcycle has two balancer shafts regardless of space and weight constraints... 🤔 It's a pretty smooth thumper, I should add.
@@xrhst0s2114 You mean the Aprilia Pegaso? Same engine, just carbureted. Mine (in a BMW F 650 CS) is relatively smooth until 6500 rpm, a bit viby in the right foot peg.
@@StephanKusch Yes I'm talking about pegaso i think it's worse with injection cause you get more power so more dorces literally I screw to spec all the bike except engine after like 2 months of riding
I have one and discovered that if I sit in exactly the right place at a certain speed it blurs my vision. It's the only thumper I've owned so I'll take your word for it. It vibrates less than a CX500, at least.
I dont think ive ever skipped your engine balance explanations, even though I have already seen you explain it before. You do such a great job and tweak the lesson each time to fit the video, so its always valuable
Man so glad u responded to this. I read somewhere that the KTM parallel twins are not arrenged 90 degrees apart but ruther 75 deg apart. This was to mimic the big brother motor used in the super dukes and super adv. So maybe KTM they want to maintain sound/signature throughout their models.
I''m with you on that ... I think KTM did 285 instead of 270 to make it sound as similar as possible to their 75-degree (with balance shaft...) V-twin engine. Mechanically, I think 270 would be "better" (as D4A so very well explains) but 285 is "close enough" and let them keep the sound as close as possible.
I learned about forging in class not long ago, and I think that you are right about the need to add a twisting motion in the manufacturing. However is is true that adding an 15° angle would add transverse forces that would not help the two parts of the die align well.
I never get tired of the explanations of primary and secondary balance and even so it is still difficult for me to understand them 100%. I'm looking forward to the video coming to the Spanish channel, maybe it will be easier to understand then. Thanks once again for your videos. I have translated this comment with Google, there may be errors.
I have noticed that on a lot of the content creators this seems to be the case or they have personal bias of one brand over another. I was raised in a Chevy dealership and I couldn't be very objective if I was comparing other brands back in the day.
What's more likely is the deflating balloon of the F9 fans and the rage that follows. I have nothing against Ryan. I just think a channel with their production slickness will box itself into corners from time to time, as fans mistake slickness of production with objective fact.
@@Ramonatho But the KTM faithful do it and don't even think about it. They pay more believing them to be superior, forgetting that many of the bikes are now made in India or China 🙂
That's a person with true passion - dropping everything they do and making a calm, profesional video help viewers understand better something they've seen on another channel. Thank you for staying true to what you do.
as a CNC machinist with 15 years jobs on shoulders at many levels, i can say you dont TWIST a forged piece you just build another die for make a different piece at a "irrelevant" price (maybe 50k-100k euros) and CNC machines for work on forged pieces can just reprogrammed at different degrees of work with few hours ^^ basically there is no additional costs for make similar pieces because all pieces need those costs 285 or 270 cost the same and if there is a difference is minimal and can be nullified by market selling another topis is about protos, when you make 1 engine and thats it there is no selling so only costs
Interesting, thank you for the explanation. Honda Transalp 750 engine also has two balancing shafts, " Primary drive gear can serve as a balancer drive gear for both front and rear to reduce weight and size. The 270-degree crank was adopted to cancel the secondary oscillation. Thanks to this application, even though the basic arrangement includes one weight for the light and compact front balancer and another for the rear balancer, the primary vibrations and force couple can be cancelled with ingenious efforts made to the layout and orientation."
I like watching you explain balance every single time because you constantly explain and update it better. Big engine enthusiast, enjoys your videos a whole lot.
I’m embarrassed that fort got no disagreements in their comments. We’re all sheep. Lesson learned here kids in all things: we always might be wrong, don’t ever let the nicely packaged stuff pass as gospel. Take the time and respect those who fiercely question conclusions and be aware of those who ostracize the doubters, as if they’re hiding from truth.
Dear D4A, I think you are quite right. I do not know anything about your academic and scientific background and I sometimes miss numbers, equations and functions, and calculus and all those beautiful engineering stuf in your channel. However I admit that those things may be boring depending on the subject and the audience. Anyway, I will try to do the math and let you know in the comments whether or not there is any chance of you being incorrect in some minor details - I just need to model the piston movement and take the first (velocity) and second (acceleration/force) derivatives. And, before I forget, thank you for yet another amazing content.
@@kwahoo5746 I suspect that the length of the rod plays some role and is being neglected and fixed at an arbitrary number in order to obtain those magic 75 degrees as the moment of peak velocity.
@@kwahoo5746 Thanks! I am not sure if I will be able to follow you that deeply, but In fact the secondary movement got complicated very quickly. Some simplifications are tempting or unavoidable to take me somewhere.
I just now realized I never subscribed to this channel. I've been watching for years, the videos always just appeared in my youtube front page and I didn't think anything of it. It is now corrected
@@AnubisTheSonOfRa I personally do feel like I was subscribed at some point. It wouldn't be a first time YT cancelled subscription without consent or notification. But I'm not 100% certain with this channel.
Very well and clear explained. That and your respect towards Fortnine shows you not only in the know but also a decent human. Actually, I accompanied a project at a crankshaft maker for three years. We set up a complete turnkey crankshaft production line and during that time I learned and saw a lot. I am no technician but still I don’t think that production of a 285 cs should be more expensive than a 270 cs. The tools within the press as well as the necessary procedures before and after the actual forging should be (nearly?) the same. At least costwise it could be neglected.
This is a very detailed but easy to understand and follow description of the way the different forces balance out-so well done sir. I have some limited experience of this having spent some time making 360, 180, and 270 degree parallel twin cylinder crankshafts-and balancing them on a computerised Schenck balancer. The crankshaft were all machined from solid using EN30B grade nitriding steel, and were in the main for Nourish/Weslake 8 valve twins of various capacities.
That sounds really 'fun', envious you got to make them. I've had to 'make do' with re-phasing Yamaha XS650's as I can't afford a Triumph plus all the parts to go with it.
I'm so glad you've been educating yourself & passing on that knowledge Otherwise not knowing no better I'd've taken F9 on his word commiting myself a disservice
Reading the title of this I initially dismissed the video thinking that intents to get clicks just by arguing against F9 , I m happy that I saw it now, you did a true and detailed peer review here, mad respect for the effort!! Needless to say your arguments are all compelling.As a scientist I am truly pleased to witness such high quality of debate in a medium that things can easily go astray..
Great article again, gave me a lot of pleasure watching it. In a 360 or 180 vertical twin, where both the pistons stop simultaneously, the flywheel must use energy to get them moving again, but this is not so in the case of the 90 and even better the 76 crankshaft when one piston is at top dead centre while the other (76) is moving at maximum velocity. However; The ideal off set angle of the crankshaft where the second piston is at maximum speed is depending on the ratio of connecting rod length to crank radius. F.I. If the connecting rod would have an infinite length there would be no secondary imbalance or secodary piston speed.
@@stevejones1318 Yes, but a great deal less problems. My 650S is 100 pounds heavier then 2nd gen KLRs. Mostly from rubber mounts. It has little to no vibration until you get to 70mph. From which; where i live it's a rarity to get to 70mph.
As a total ignoramus concerning the fine details of ICE technology who chanced on this because the algorithm/leprechauns thought I needed a change of life focus (?), I have to say thanks for the new info and I am *hugely* impressed by the clarity, enthusiasm, and fair mindedness of this presentation. The diagrams were particularly useful. Excellent work!
The moment I saw Fortnine's video, I knew this one was coming. There's no way you would leave a engine balance topic out in the woods. Nice work (and I like Fortnine too, awesome channel)
I might be wrong but after a quick calculations it seems that the highest acceleration point depends on the ration between crankshaft radius and connecting rod length. The smaller the radius and the longer the rod then the max acceleration point is closer to the 90 degrees. The minimum seems to be around 64 degree when the ratio between crankshaft radius and connecting rod length is somewhere close to 70% - 86%. The mentioned 75 degree is correct only when ratio is around 30% (so the rod has to be about 3 times longer than the radius). By the way, I love D4A videos and I'm his big fan. Keep the good work D4A!
Yes, d4a should say "about 75 deg, depending on crank radius to conrod length ratio", since all small (motorcycle/car) engines are around 30%. According to S. Luft "Podstawy budowy silników" the ratio is: SI engines: 0.25 - 0.28 (inline) and 0.27 - 0.3 (V), diesels: 0.24-0.3 (inline) and 0.27 - 0.3 (V).
Your explanations are brilliant. I came to this channel with the most basic understanding of how engines work, but learn a lot from every video, and find them all fascinating. My respect for mechanical engineers has also increased massively. Also love your to communicate the complex, in understandable terms, and with humility.
I suspect KTM does the 285° inline twin to more closely match the character of their 75° V-twin, which I assume they do because it packages better than 90°.
yes thats the reason. I've checked their marketing material and they dont claim to have better balances in their engines. so its completely a matter of preference.
As soon as I watched that Fortnine video, I was sure D4A will come to the rescue because I smelled bullshit. He didn't give explanations, just claims without evidence and also that forging process becoming expensive because of an extra twist seemed very under researched. Thank you D4A and kwahoo_archive
Sticking with “facts” is why Driving 4 Answers is such an awesome channel. And your respect of other TH-camrs is commendable. It was not a case of the other person being wrong…, rather just incorrect.! 10 out of 10.
Twisting a crankshaft after forging has no additional significant cost associated with it, even more so if the price charged is premium. I had to call up a friend working at the Bajaj/KTM/husqvarna factory to verify this. While the factory he works at doesn't manufacture KTM's over 490cc , He worked in Spain factory before with larger engines. Here is the direct text from him " Balancer is in all engines from 250. Brand goes for that few percent of performance so used 285. Bigger ones use V twins and sell more. Cranks are made with same machine for 790 and 1200. dye is different thats all" Original text was in native language and I translated it so grammar is not right.
... and "dye" is misspelled (in this context); Dye (noun) is a substance that imparts color; die (noun) is a tool for imparting a specific shape to a material.
Acceleration of the rod also contributes to force. This rod force has components both parallel and normal to the stroke. The crank exerts a force normal to the stroke, as well as along the direction of the stroke. If I get ambitious I might work out the rod force, along with the piston and crank force, vs. time.
Thx, I was always asking myself why everybody speaks only about piston forces and nobody speaks about the conrod forces. Are they so small that they are neglected ?
@@gsbeak About (IIRC) 1/3 of the conrod mass is considered as a mass moving linearly with the piston and about 2/3 as moving circularly with crankshaft journal. The mass in linear movement is added to the piston mass, and the mass in circular movement can be balanced with crankshaft counterweights.
Thanks for your response. The 1/3rd 2/3rd approximation is very useful to know. The motion of every point in the rod can in principle be calculated, and the effect of that point’s mass can thus be calculated. The overall sum of those forces can be calculated, too. Though I use finite element analysis tools, the ones I use are for electromagnetic field problems. So if I were to undertake such an analysis it’d be pretty crude. But the tools for the mechanical analysis definitely exist. I might suppose the con rod lateral forces are quite closely related to the inline piston forces. Just a guess, though.
@@maxenielsen I think, this can be done even easier, without FEA, since we can consider the conrod as a rigid body. Calculate the center of mass, and the moment of inertia. Then multiply them by linear and angular acceleration respectively to get force and torque. This sounds like an interesting exercise, with a small help of CAD tools to estimate conrod properties...
@kwajoo5746 Yep, I agree that FEA IDT necessary because, as you say, the con rod can be described by its center of mass and moment of inertia. It’s interesting to think about the torques applied by the crank and wrist pin. Thanks for your comment.
Very interesting. I didn't understand any of it, but watching FortNine's video almost had me trading my "plebian Yamaha" for a KTM. What a fool I would have been!
That low frame rate is a sign that you had to get this out as fast as possible so people wouldn't be misled. I appreciate that dedication. I'd like to add that regardless of whether or not Ryan is wrong about 285s, I still prefer them. I find that they sound better to me, with the 270s still having just a hint of that nasty 180 sound at high RPM. The next best one is the 60/300 degree twin, but that can sound too much like a cruiser at times to be in a sport bike, IMO. Still leaps and bounds better than Harley's sound, though.
The Harley 'potato-potato' is due entirely to the crappy intake they have and 'charge robbing' at low rpm on carburated bikes. The fuel injected bikes deliberately mis-manage system at idle to replicate the sound. HD spent over ten years trying to sue Japanese cruiser manufacturers as they 'patented' the HD sound
@@Drunken_Hamster Nope, I was teaching Suzuki F.A.S.T. but spent a lot of spare time over at HD which is why I know about it. I forget if it was 2007 or maybe 08? I attended several HD lectures over 2 years, but, being Suzuki, couldn't, take the HD factory tests It was when fuel injection was available but most bikes still had carbs (maybe FI was optional?, I forget) I probably have paperwork on it somewhere safe, still fixing things from Hurricane Ian in Sept 2022 with a lot still in boxe., MMI wanted instructors to get as much knowledge as possible, majority of import instructors had less than zero interest in Harley but I always want to know more. Had a few good friends there who really liked discussing differences between USA market and European/British market. (plus a few A-holes who wouldn't speak to me 🤣 😇) One Cajun instructor asked me to bring a translator (he was a right dick who got canned for telling a female student she should be 'at kitchen sink, barefoot and pregnant')
I agree with balance. Let's look at torque production. More importantly let's look at how the firing order is striking the tire. Does the tire have a recovery time from ignition shock? Another well made video.
Yamaha's big deal with the cross-plane-crank R1 involved the rotation speed of the crank being more uniform because it never had all pistons starting and stopping together the way a conventional inline-4 has it. Off the cuff I'm thinking the 270 twin will be closer to achieving this than a 285 twin, and this was only briefly touched on in this video, but the math starts getting really hard! The uneven-firing-pattern and tire-recovery situation seen in MotoGP is a whole 'nother situation on top of this, the ever-so-vague "rider feel" playing a part, with the current (known) interesting best example being the Ducati 90-degree V4 with 70-degree-offset crankpins.
This was a beauifully simple explanation to something that is much more complicated than I initially thought it would be. Thanks for taking the time to create, edit, and share
Thank you very much for making this video. I spotted the mistake in the video immediately, but I do not have a TH-cam channel to discuss it. Fortnite has mistakes in almost every video as well as "engineering explained".
I enjoy your video's very much but as with F9's video I say, "Pffft. Husqvarna's Nuda 900 model, designed & manufactured under BMW ownership, had _the_ best version of any of the modern parallel twin variants. They took the Rotax manufactured 798cc BMW engine from the GS800 and increased the bore & stroke by 2 & 5.4mm for a total of 898cc. They then offset the firing order to 315° from 0. Husky took a characterless, _agricultural_ sounding engine and gave it more character than the Toy Story and Shrek cast combined. It sounded amazing, the bike looked hilarious and it was enormous fun. When I added a Remus slip-on, unbelievably, it sounded even gnarlier (baffle almost always in - I'm not a monster!) In fact it sounded so good it received as many looks as a mates Diavel. Apologies for the lengthy post. I wrote something similar in the F9 video's comments and it was completely ignored. Only ~3,500 Nuda's were built (incl., the R variant) and this bike was just cool enough it shouldn't be forgotten 🤘
I looked for a comment about the Nuda. An amazing piece of italian engineering (Husqvarna was based in italy under the BMw ownership), it sounded like an Harley (same firing intervals of a 45° V Twin) on crack. Both the frame and the engine are the outcome of the italian passion as the red heads of the cylinders (trademark of the Italian Husky engines, see AJP pr7 monocylinder) prove.
I often dream about getting myself a 800 gs and upgrading the engine like it was in the nuda. Its a dream bike but maybe too raw and focused on beeing fun that it could catch on for its price. its similar with the hypermotard and other twin bikes trying to be fun bikes for of all and only secondary useable as a daily.
@@d4a yes, Spite's corner did a video that's not directly saying Fortnine is wrong, but that some of their research videos, made with sample size of 1-2, has been taken by novice riders as gospel. Example includes their engine oil analysis during engine break-in of different brands. I forget the other example but I am sure it had to do with a quick repair hack type video.
@@manitoba-op4jx you're right actually, but that's their niche. Completely new riders getting the hang of new terms. Its like an "Introduction to Motorcycling" sort of channel with outstanding production value. Of course every rider should do more research after the introductory videos from Fortnine.
@SMTahmid they specifically point out that the sample size in that experiment was tiny. You can't fault a creator for the generally statistics illiterate youtube audience.
Awesome video. As for KTM choosing a 285 interval, it's important to remember that their V-twins use a 75-dgree spacing (IIRC, some of the engineers who designed the original RC8 engine were originally responsible for designing the Rotax 60-degree V-twin used by Aprilia, and they incorporated the lessons learned there in designing the KTM engine, namely spreading out the cylinder to reduce interference at BDC, while being more compact than a 90-degree set-up). In designing the LC8, choosing a 285 crank allowed them to keep the same sound signature as the LC8 (also gave them a certain uniqueness)
And we need someone who does testing to step in and instrument both types of engine and see how the real world compares against the two sides of the debate.
Great video - more engineering, less hype! I have an '06 Honda crf450x (single cylinder) with a single balance shaft, which holds vibration down to an acceptable level for riding offroad. Because this engine has low rotational inertia, it will rev scary fast. When it comes to engines, everything is a compromise; off road applications favor weight reduction, while on road favors smoothness.
So you missed my comment to Fortnines video? 😉 I corrected the Fortnine video in my comment, and also added the historical reason presented by KTM! As you guess - it IS a sound/character thing, not an attempt to minimise vibrations. I’m pretty sure that most engineers reacted to the videos erroneous claims, but youtube-viewers don’t always point out wrongs they see, even if they are engineers. We are not all difficult, just… you and me. ☺️
Just excellent - took a lot of guts to 'review' Ryans vid, but so refreshing that someone did without making it personal. I am a fan of both as I think both are very good teachers.
I wouldn’t know if you were right or wrong, but you explained things in a way I and others could easily follow and have a reasonable idea of what to look for in reference to not only these engines but many others. Good job.
Just in case someone is still confused. In the beginning I say how peak velocity is 75 but then show a graph where it's at 90. To understand this you have to keep watching because at 08:45 it's made clear how 75 is with the rod, 90 without the rod. When we speak of primary balance alone we imagine that the piston magically moves up and down, we pretend it's a free piston because we are isolating it from the rod to observe its forces. When we add the rod we get the total. In the beginning I speak of the total and then about the primary, but I don't think I stressed this properly so maybe that's why a few people got confused?
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Thank you, this was all very interesting material.
I always thought that the largest source of secondary vibration came form the counterbalance weights on the crankshaft. These are rotational, and so cannot do more than a "passable" job of counteracting the reciprocating and rocking forces. That is what I had always read when I was young. This balance weight was supposed to approximate the piston weight, plus a part of the conrod weight. There can to be only a "reasonable" balance applied for all the reasons you point out about how pistons and conrods generate their forces; but mainly because at ~90 degrees that counter weight is creating a sideways force. I have seen illustrations of patents for engines using two crankshafts and conrods per cylinder to counter these half-stroke forces.
The most commonly expressed way to balance the piston weight without balance shafts is the use a 90-degree V-twin with ~100% balance weight on the crankshaft - the half stroke forces from the piston tending to balance against the second cylinder's piston. As the two cylinders usually share the crankpin, the rocking couple is also small. In reality you can never fully compensate for *all* the out-of balance rotational and linear forces.
If my memory serves me well, there are a few other really minor things in your presentation that were a tiny bit in error.
I am reasonably sure that there was an mid-'70s Yamaha 500cc 2-stroke single motocross bike that used a balance shaft - and probably needed it! This was not at all a common bike, but when I was buying my TY250 I saw the ads for it, and thought it's technology was interesting. I recall it had only 4 speeds in the gearbox; presumably to fit more robust gears into the narrow crankcase?
The other comment you made concerned the use of "big bang" technology, before the idea made it to the MotoGP "big bang" 4-cylinder 2-strokes. But the advantage of "long" pauses between the firing impulses was known in British big singles. I read about it in a UK magazine about a decade before those 2-strokes, in reference to a BSA 441 that had been turned into a road racer. It was noted as losing out badly to multi-cylinder 500s on the straights, but having better traction on the corners due to the relatively low revs and relatively large flywheels leading to the tyre still driving the bike between the impulses, and remaining in non-slip contact. Combining slow-revs with big flywheels to drive through areas of poor grip was exploited widely in Observed Trials. Modern Trials bikes have taken a very different direction.
You are wrong!!!!
Just giving you wanted to see in the comments! 🤪
Thank you for your explanations of mechanics (physics?) in all your videos.
Teachers should strive to be as clear as you are..
I heard pistons on 70s two stroke Kawasakis are not semetrical in mearsument ant material thickness to adjust for thrust offset and exhauast heat
My take is if it need balance shaft adding to rotating mass then design is not elegant
Nitpicking is fun, and I’m here to tell you that Irving actually suggested 76 degrees ATDC for maximum piston velocity. 😊
An intelligent and thoughtful man respectfully and succinctly peer-reviewing another intelligent man's work, all while acknowledging the FortNine channel's brilliance and success. This is A+ content.
Don’t forget to clean yourself up with a Kleenex.
Kleenex has that gross waxy lotion infused into it. Paper towels is what I prefer.
That's what real men do. It takes a lot of self reflection to overcome the ego.
👍
Now to see if they have the integrity of removing their video... If they do I will keep watching if they dont... well it was good while it lasted.
As a fortnine viewer, this should be interesting.
EDIT: The respect you show to him as a viewer and also a creator in a similar space is NOT TO BE UNDERMINED. Its so different than just going at each others throats. You two are awesome!
Yeah. I quit watching him years ago after so many mistakes and pushing his opinions as fact. He's a hipster rich kid who knows a few things, enough to sound like an expert but far from being one.
@@VndNvwYvvSvv Ryan is a salesman. Ever since the channel took off I did notice a hint of ego in each of his videos. In the end, he's really just a salesman and fellow rider.
@@BRZDRRyan has a degree in physics from one of the most prestigious universities in Canada...so there's that.
@@Kevimoto He has been a social media influencer for all of his professional life. A bachelor's degree from 10 years ago is a helpful starting place for knowing how to think about science, but it doesn't give him any usable expertise. He is a very intelligent and knowledgeable person, but his profession is content-creator, entertainer, and marketing professional, not educator, journalist, scientist, or investigator as some of FortNine's content portrays him.
I know I know I know what Ryan is! Pick me!
He's a person. A person that obviously works hard to entertain and inform you. I prefer to enjoy and appreciate what someone does rather than try to pin subjective labels onto their personalities or careers in an attempt to somehow minimize their achievements and make me feel better about myself.
As a trainer/lecturer I must congratulate you on the clarity of your explanations and the use of visuals to illustrate the concepts
As a fellow who has been described on more than one occasion as a sandwich short of a picnic, I agree. If someone can knock knowledge into me, they can drive a thumb tac into a brick with a broken finger. This guy is good.
What about adolf
... though I'd have loved to have seen the overall imbalance graphs with the easily-counteracted primary vibration subtracted, to see what is left over.
absolutely
better than college
Yeah, I did think the 285° thing sounded a bit off from previous videos and research I had seen about engine balance and crossplane engines, but I didn't have the time to check F9's work, so I'm glad you did.
As far as the forging goes, yes it is cheaper and easier to make a 270° crank than a 285° crank. When forging a 270° crank, you can set up the 2 halves of the forging dies so that you forge in one journal then turn the crank 90° or 270° and forge in the second journal without affecting the first journal. Due to how the two forging dies come together, you can't really do that if the journals aren't either parallel or perpendicular to each other. Thus, for a 285° crank you would first forge in the journals for a 270° crank, then use a separate machine to twist the crank that additional 15°. Since this requires a completely separate machine along with an extra step, most companies just stop at forging in the 270° crank.
Hi r.j.bedore9884. You seem like you are very confident in your statements re: twisting of the 285 degree crank after forging. I'll be honest, both these guys seems to have a much better grasp on this than me... although I understand the math, but not the manufacturing process. I am just wondering where your confidence comes from? Are you someone who actually has some experience in this field? It certainly seems so... I'd be curious to know. Thanks! :)
@@steveblackwood1202 I have some experience with creating forging dies while getting my engineering degree in college, but I will admit I haven't forged a crankshaft myself. This is just what I remember the guy heading our machining lab telling us when one of the guys in class asked about making a new crankshaft for an old motorcycle he was restoring and having trouble finding parts for (this was back in 2006/2007 before buying parts online was as easy as it is today). Because forging generally involves smashing two large plates together with the shape you want carved into them, you tend to have trouble making dies that would let you have angles that aren't either perpendicular or parallel to the direction the forging press is moving in. For crankshafts whose journals aren't either all in one plane or perpendicular, you can either forge a blank then twist it, forge multiple pieces then spline or bolt them together at the correct angles, or machine the entire thing from one large billet of material. Making the forging dies can be expensive, but making the parts with them is faster and cheaper than the other methods, which is why most mass produced parts are made this way, and why most parallel twin bikes have a 180° or 360° crankshaft since that is easiest to forge. Machining a part from a billet is more expensive per part, but if you are only making a few for a prototype, or say for a race engine, this is almost always cheaper than getting a custom forged part. Hope this helps.
@@r.j.bedore9884 thanks! I appreciate the explanation.
@@r.j.bedore9884 Most parallel twins are 270° now.
@@seth094978 No, while 270° crankshafts are becoming more popular, many are still 180° or 360° like the Kawasaki Ninja 300/400, Versys 300/400/650, and W800, the Honda CB500 series of bikes and a few others, several BMW parallel twins, some Royal Enfield bikes, and until recently nearly every Triumph parallel twin was a 360° crank. I think there might have been some Yamaha cruisers in there as well, but I'm not super familiar with those, and I'm not sure about Suzuki since I'm mostly familiar with their V-twins. Also, I believe the motor in the RS660 and its sister bikes is the only Aprilia parallel twin with a 270° crankshaft. Thanks to the popularity of the Yamaha MT-07 and KTM 790/890 bikes, crossplane crankshaft twins are certainly on the rise, but they haven't taken over the market yet.
Life hack:
Hydrolock one of your KTM cilinders to fix it back to 270º
Why dont manufacturers use this trick instead of making the crankshaft glow orange and twist like cave men?
@@L3v3LLIP because big glowy does not want them to
See that's what they don't want you to know
bent rods wont help you do this.
@@RealDougFields you just dont know how to do it correctly
Each time you re-explain secondary balance, you do it better 🙂
Where is the Fortnine / D4A collab we all want?!😊
Yeah, really
unreal engine update fire 💥💥🥵
This would be awesome indeed! I would imagine both of these guys having a thoughtful discussion about this topic, and then having a few laughs about plenty of other things. Could make for a terrific live podcast type of interaction.
@@matthewpeterson3329 yess :D
they can name it 'internal combustion' :D
Independent competition is a healthy thing in the public sphere.
as a mechanical engineering student who has done a semester long project developing a MATLAB model simulating exactly what is discussed in this video (acceleration and force modelling, advanced kinematics and kinetics of mechanisms) i have to say your style of lecturing is WORLD CLASS, you never lost me once during this video and I imagine even someone who has never taken high school physics can follow along the fundamental concepts explained in this video, even though you make no sacrifices in justifying your claims. Well done!
Not saying the video wasn't good, because it was. But "not losing a mechanical engineering student that did a semester long project in exactly what's discussed in the video sounds like " sounds like the absolute bare minimum no?
No, not really. It differs from person to person, but especially in mechanical engineering, sometimes you get a professor that does not do a good job explaining complex topics, so you can get lost pretty quickly. I think what he meant was that even with his knowledge on this, it was easy to follow, simplifying it enough that it is digestible for most people. One can also get lost when someone is explaining a topic that you already know. I remember once that a classmate of mine explained smt in thermodynamics that I already was familiar, it was just the way that he explained it that got me confused and lost. @@AirSKWolf
Were you able to follow this at full playback speed? 0.75 was much better for me.
@@daegueric - No shame whatsoever in that. That's how I watched it.
As someone that wanted to study mechanical engineering and chenged my mind, oh Man, 6 months doing a project in MatLab, I chose my career correctly 😂😂😂 just kidding, I don't have enough patience to do that kind of work.
I'm a machinist who works with fixtures and dies, and I have a lot of manufacturing experience. I came to the same conclusion you did about the manufacturing process after watching Fortnine's video. While I may not have much experience in an engine manufacturing plant (very little and none relevant to the question at hand), It seems to me that creating a die and platen that can stamp out a 270 crank would mean that you could do the same for a 285 crank just as easily. From my experience, the time and cost difference to make the tooling would be negligible. Again, I have no experience with heavy forging like what you would need to create a crankshaft, but I'm having a hard time believing that it would take any extra steps to create a 285 crank vs a 270. Even the finishing machine work would be very similar.
Just want to say much respect to you brotha ... my grandfather was a tool and die maker and that is a dying art so I say much love and respect to you my friend and thanks for the good memories you reminded me of when my pepeir was still alive and well and owned his own land and such he had a big red barn (go figure right all old barns lol)and it was full of nothing but machinist tools , giant lathes, mills , presses and all kinda shit I still don't know but they were so cool and all done by hand and man did he make some cool stuff ... rip to him but man if he was in his prime doing that as I am building cars now , me and him could made some super radical 1 off parts for mooorrrreee powa baybay 😅 lol ... peace and love bro keep it rad stay safe and build on l8z fam and much respect to you friend
If it's a 3 journal crank you could even use the same forging dies; just take a freshly forged, glowing hot 270° crank and twist it ever so slightly to make a 285° one. It's an established process on crankshafts for engines with more cylinders- th-cam.com/video/mj8leWsB4w4/w-d-xo.html
Tooling is tooling. It would be more expensive to retool for 285° or whatever other offset you want than to continue to produce whatever you are already producing. If you are starting from scratch, you're going to be tooling for whatever it is you want to produce, it will be no more or less expensive to set up for 270°, 285°, or 180°.
Hello, I share your opinion @operator0 but I think that adding an 15° angle to the die would add transverse forces that would not help the two parts of the die align well (could still be achieved??) ... But I am still a student in this domain so take it with the biggest pinch of salt.
@@kender1412
That's the exact same reason that Boeing still makes the nose of their 737 the same, even though more efficient shapes have been found. "Tooling is tooling," and reshaping would require different tooling, so the legacy shape remains.
wow.
a professional and respectful critism to my favourite motorcycle channel.
I no longer have a favourite motorcycle channel anymore, from now I have 2.
:) thank you very much for taking your time and correcting their mistake.
Please consider collaborating with them in their future engineering related content.
now if you excuse me I'll be binging your videos :D
Thank you. That's the attitude I really hope to see after this video. I really don't want this video to take away from the amazing content f9 produces. As I said this really is a complex topic and all the other points in their video are excellent
@@d4aGreat video as usual! I would love to see your take on some more motorcycle engines, potentially comparing v-twins? Ducati vs Moto Guzzi vs Harley vs Indian etc would be pretty cool, maybe too many for one video though!
Thats a great idea actually. "The many faces of the v-twin"! Thank you.
@@d4a wow thanks for the reply, I'm glad you like the idea! A video on desmo valvetrain alone would probably be a lot, and then maybe euro v-twins could be one, and American v-twins as another... Just thinking out loud. Lots to cover but whatever you end up doing I'm sure it'll be great. Thanks for all the content!
@@d4ait’s not a competition. I think this is an incredible addition to Fortnines video and you both spread knowledge, unbiased and politely.
Nice! Two of my favorite youtubers in constructive and respectful debate! This is so insanely wholesome compared to the usual primitive beef amongst communities. My inner scientist is happy
This is more monologue than a debate :) But thank you very much.
With a few notable exceptions, that's how scientists critique each other. The usual mud-slinging is by people not educated in the scientific method.
@@d4a please consider reaching out to them for their future content. I'd love to see Ryan's humor and your professionalism in one video.
It is no a debate... yet :D
@@d4a
It's important to note, this is the exact same setup it took for the great Steve Mould / electroboom debate of 2022.
It is always said that the main reason the KTM LC8c parallel twin has a 285 degree offset is to mimic the feeling of the bigger KTM LC8 V-twin engine which has a 75 degree opening of the V. And thank you for this explanation, it was great!
Yeah, this is the reason I first heard as well. Though I admit that I liked F9s interpretation because it “elevated” my 790 into a special premium category that could have been used for a few extra bucks on resale. But not anymore. Damn.
After some research, I found exactly the same, but on a BMW f800gs, crank is 180, but the firing is 360 due to the layout and in result it will mimic the sound of the R1200gs (that rich sound of the boxers)
There is a diagram of the BMW f800gs 360 degree crank at 14.53
@@steamixion (I did before watching the video, but tks anyway) I can't stand the vibration in my 800GS, really annoys me, looking for a V twin now. (probably a Vstrom 1050de)
Phil Irving's original driver for proposing 76 degree crankpin stagger (referred to here as 285 degree), was to use the maximum inertia of one piston to help the other over TDC; in other words, to reduce the size and weight of flywheel required for low-rpm running. He was grappling with the need for more flywheel effect on the AJS Porcupine, and had vast experience of the assistance of one piston for another on V-twins.
As the presenter here notes, crankpins at 360 degrees, 270 degrees and 285 degrees are all have their advantages. All can be fully balanced with balance shafts, but 285 degrees maximises the free flywheel effect.
By the way, Irving's 76 degrees (effectively 284 degrees) was based on conrod to stroke length ratio of 2:1 - common at the time.
The 285 degree parallel twin most commonly mimics KTMs 75 degree V-twin. Turns out it is a KTM brand character thing and nothing else. Great presentation!
Exactly. Well said. It is close in sound however my ears prefer the KTM’s inline twins.
As 270° is imitating a 90° V twin.
And the forgotten Husqvarna nuda 900 (italian engineered high-bored f800) has 315° crankshaft, mimicking the 45° V twin (Harleys).
This is the correct answer. And lets not forget, parallel twins are just the cheaper to make alternative to the real v-twin as you only need one cylinder case and half the camshafts. And you also get rid of the cooling issues of the back cylinder.
@@user-lw6iz7zy2o Agreed. Plus it enables more space than any V twin for a bit of creativity and possibilities.
@@user-lw6iz7zy2o The cooling of back cylinder issue only applies to air cooled v-twins.
As someone who does not have any background in any types of engineering, I found this video and explanation to be extremely enlightening. If you can bring Normie’s along for the ride in such a way, I think you’re both winning.
0:24 There’s not a man been born yet that’s never made a mistake
Exactly!
Yes, there is. He's never done anything.
I thought I was wrong once, but I was mistaken.
@@phillgizmo8934to live that way would be a mistake
Once, there was a man who went through life denying all of his mistakes, surrounded by lawyers to make the wrongs right.
You don't wno me (opps)
I am one of those 50% so I will correct you :D
TL:DR The reason KTM went with the 285 is experience. What once used to be a necessity for creating a compact V-Twin has helped KTM in creating a well performing Inline 2 without having to start from scratch
Back then KTM only made single-cylinder bikes. The idea for a KTM two cylinder idea came from a university student project; a V-Twin made from two KTM dirt bike singles. The students didn't want to use a 90° cylinder angle because the engine would be too long. So they decided to move the cylinders closer in a 75° arrangement with a multipurpose shaft between the two cylinders which balances the engine and drives the water and oil pump aswell as the the alternator. Shortly after Pierer started developing the LC8 (Liquid Cooled 8-Valve)
The basic arrangement stayed until today. KTM spent more than a decade on perfecting the 285° V-Twin so when they wanted to join the midpriced segment they designed the engine in a way that they can use their knowledge from LC8 development to make the LC8c. (c for compact)
70% of the explanation went straight over my head but man I really enjoyed watching this. Well spoken, well detailed and laid out, awesome video 👏🏾👏🏾
Awesome to see a video response from you to the F9 video. To me the only thing that felt weird originally watching the F9 video was your last point on the production of the crankshaft. Instinctively it feels there shouldn't be a difference. Yamaha for example also makes the CP3 engine with 120° between cylinders so it's not like Yamaha can only do variations on 90° affordably.
Your physics are spot on and so are your conclusions. A couple of minor points. (1) the angle of the peak velocity can be different depending on the length of the connecting rod relative to the stroke. The specific equation can readily be developed with a little trigonometry, it can also be found in Taylor and other engine textbooks. (2) a primary method to reduce the first order vibration are the counterbalances on the crankshaft itself.
Now open the Pandora box on balance opposed (e.g. Boxer) engines. Perhaps an upcoming video of yours
IDK if he ever mentioned what you said in point 1, but I know that many times he mentioned what you said in point 2. Just not in this one. I'm almost certain he did cover boxer engines, but it could have been in the video about something else. I would have to check.
Excellent point about the variable nature of the secondary imbalance with rod length. Ideally we would use rods of infinite length, but there are packaging issues...
I legit was like "wth is fortnite doing with engines?"
Fr 😭
Same
Same!!!
Me too
Fort9 has lost their 'way' so trying a few different things. Phil Irvine was a legit legend...
This is how someone who knows what they're talking about proof reads someone else's work. Beautifully done! So nice to not click a video and listen to bitching and snide comments, just eloquent facts and research.
Love the channel dude, cheers!
One of my favourite bikes ever was my 1998 Yamaha TRX850, a splendid machine that was the first (mass market) 270 degree parallel twin to hit the streets.
An old acquaintance of mine owned one of those when they were brand new. He loved it, and I was in awe of it. On paper, they appeared to be a fairly "middle market" machine.
He was the first to admit that top speed wasn't its strong point, but in the "real world", he could round up just about anything on that bike. And when I say "real world", I mean on the track at ride days, as well. Yes, CBR 900's would have him on the straights, but at the end of a lap, there was nothing between them. And on the road, nothing could keep up with him, and he wasn't riding like a lunatic, the bike just did it's "thing" with ease. I would have loved to have ridden it but never got a chance. l don't know why I own a Kwaka. I'm a huge fan of Yamaha.
@@davidbrayshaw3529I had 3 .... Did plenty of trackdays on them ... The genius of them is they made you look much better than you actually were.... Only negative was a gearbox like a bag of bolts....
@@stevebayross7248 I wasn't aware of the gearbox issues. That's very un-Yamaha like.
You're pretty much echoing the words that my acquaintance said.
I always thought that they were a fantastic looking bike, too. Great note, to boot.
I worked at a dealership when the 'Super Tenere' XT 750 came out. That was in late 80's.
Yamaha barely mentioned the crank design.
A 137mph trail-bike was totally crazy (I did one of the very first modified carb / air-box / exhaust ones)
@@davidbrayshaw3529 the Yamaha gearbox is almost always terrible the first year, usually second gear breaks'
Always gets fixed second year with stronger parts that retrofit early models.
That was my experience at dealers until I left in 1990
Thanks! Number 4 error is that 270 crossplane cranks is NOT a new thing! They have been around for almost thirty years in Yamaha TRX's and TDM's!
I had issues with Fortnines claim. I do however rarely comment on anything. So this is one of those rare occasions! 😅 Keep up the good work. As a certified gear head your channel is one of my favorites. 👌
He says a lot of things that aren't true. Especially when it comes to what gear or parts are best. He has enough shallow knowledge to pretend to be an expert.
Fortnine is wrong in many of his clips. His presentation of the issues, however, is top tier and very entertaining.
the phone mount video hugely comes to mind, that one was pretty bad
@dylanc2806 I mean they did fix that one up properly in what, 2 days?
@@Ramonatho ummmm... our definitions of "properly" may differ a little. they re-released the video but i still had some qualms
Very few channels write their content scripts with such quality, mechanical accessibility, and wit like FortNine. So many wonderful lines semi-hidden in the presentation. One of my favorites, "it's said that every time a CBX hits redline a mechanic finds his 10mm."
yep. In an older video they used unscientific tests on some gear (was it helmets? oil? both?). I pointed out the issues in a comment but they were not addressed.
Love their story telling, but I won't trust their tests
Lol I commented on that video yesterday - "I can't wait for D4A to take this on!" =D
The KTM doing 285 cranks is similar to how OMEGA has co-axial escapements, it's essentially marketing.
Yup, the 285 crank exists for the same reason as the 270 crank became popular after the MT-07 (though it obviously existed long before that). It's marketing the exhaust noise and engine "feel", imitating that of a 90 degree V-twin. There's no actual real world performance benefits to this setup over a 180 degree twin, if anything the 270/285 need balance shafts where the 180 doesn't. But the 180 sounds flat and has a lumpy feel. The 270 degree crank is being widely used because customers liked the sound and feel of Italian 90 degree V-twins in the middle weight, with the parallel twin being vastly more economical to produce and fit in a smaller frame/overall wheelbase.
Except d4a's graphs are all wrong making this entire video incorrect. If the piston reaches max velocity at 75 degrees, it's force will cross zero at 75 degrees. The wave is squished at the top, it's not equal top and bottom.
@@gamebrigada2 Have you tried emailing him this? Seems that's the most likely place to get an answer
@@DefinitelyNotJ749 Ha didn't realize that. Emailed.
Yeah even the 75 degrees depends on the rod/crank proportions. A different engine will have a different angle.
I’m a huge fan of d4 and fort - my only favs. I am so grateful that d4 pushes me/its audience more than fort in grasping the more difficult. I love it when my brain hurts.
I actually found that Fortnine video very strange, so I'm glad you ended up explaining these things in more detail. Thank you
This is great! And the TH-cam algorithms worked great, too, since I just watched F9's video on this yesterday. You sir, are truly a top level teacher!! 👍🏼👍🏼
Čestitka za milijun subscribera!!! Videi su ti za svaku pohvalu, uvijek nam preneseš puno znanja na jednostavan način i hvala ti na tome što obrazuješ ljude širom svijeta!!! Pratim te dugo vremena i srce mi je puno kad vidim ljude iz regije kako uspijevaju na youtube-u, ali mi je pogotovo drago zbog tebe jer daješ inspiraciju i meni i drugima da se bavimo automobilizmom i mehanikom. Lijepi pozdrav za tebe i tvoju obitelj, neka vas Bog čuva i sve najbolje u budućem radu!
Prvi put vidim ovaj kanal i odma mi je palo na pamet da covjek izgleda kao Srbin. Nista nacionalisticki nego me bas zanima da li sam pogodio, jer po lajku komentara ocigledno jeste balkanac 😂. Pozdrav iz CG
@@Dzerom-on2zh nisi buraz
Finally an actual analysis and explanation. Fortnine makes great content, but as an engineer, it frustrates me how he gets the reasons wrong for many things. He explains things beautifully, but I believe he misunderstands fundamentals of why engineers make certain decisions. Same thing with his materials video.
At 18:37 the 5-cylinder crank fairly clearly has the pins at the correct angles; no.3 is horizontal, 2&4 are 144deg out (furthest from the centreline), and 1&5 are closer to the centreline.
Unless there's some weird overhangs on the crank I don't think there's any reason to twist it, the forging dies can be made to the final crank pin positions without a problem, just anything other than flat-plane needs more complex dies with deeper (more difficult/expensive) machining. The only time I've heard of twisting a crank was one of Audi's DTM engines, turning a cross-plane V8 production crank into a flat-plane V8 for racing, and I'm not sure I believe that other than as a justification for skirting the rules.
Sometimes they're twisted to pre-stress the steel to mitigate tertiary vibrations. Not because it's necessary to get the shape.
i respect this guy. i remember he debated about brakes and even some engineer ( as they claim ) were wrong and i agree what he said. sometimes someone who has higher education or a degree may be wrong . just like Veritasium who did a debated about acceleration of energy can move faster than what energy it has. thats the beauty of science though. you debate and prove each other wrong and the accept it as when they been proven wrong. thats how science becomes more accurate because when its proven wrong or right it added the level of extented experiment to validate.
I propose a 277.5 degree offset so you have half of both hehe
and 1.5 balance shafts
@@LeoNidasPlayForFunmake it use 7 valves, too, with one that doesnt connect to anything but has a deep well behind it, just to add complexity and keep the mechanics on their toes
@@ulogy
At that point, might as well have a three to one exhaust manifold, with one just capped off.
@@LeoNidasPlayForFuncame here to say this; you beautiful bastard!
@@Fightre_Flighte True, maybe make the air intake have a second, smaller filter right before its output as well, and require a special tool to service it.
You are the BEST, my man, at explaining these types of mechanical issues!! Your graphics and explainations are superior to any others I have come across on YT, or anywhere else for that matter! Kudos to you... especially since English is not your "native" language! BRILLIANT WORK!! 👍
I also got a bit shocked by the better 285 better balance affirmaton on fortnine's video. Thanks for analysing that fact. At least I completly agree with the polution reason for the return to that configuration nowadays,
Why does anybody produce them if they are harder to produce and have worse balance?
@@tedarcher9120 They don't really have worse balance but they also don't have better one. Also, I doubt they're significantly harder to produce. It's all in the video.
@@tedarcher9120 ktm's v-twins are 75 degrees apart, so I assume they make 285 inline twins to keep a similar sound signature.
@@tedarcher9120 Maybe for the sound and the uneven power transfer to the wheel, don't really know...
@@snapcountersteer I was going to say this if someone else hadn't already. Why KTM's LC8 V-twins have run 75° instead of the more common Ducati style at 90°, I'm not really sure. Packaging a Vtwin with a wide angle is a problem in bikes. V-twin engine are already expensive to manufacture and make everything else more complex (cooling, intake, throttle body packaging, airbox, exhaust routing, transmission placement, camshaft actuation, and a lot more). I think the crowd who loves to criticize the lowly "parallel twin" engine configuration does so on the basis of having an emotional connection to V-twins, which of themselves, are sort of a historical rebellion against the trend of inline-4's. I'm not really sure even the Vtwin folks who criticize parallel twins understand why they have the emotional reaction they do.
Sound signatures between a Ducati and a CP2 Yamaha are nearly identical. Close enough to be hard to distinguish. Certainly the vibration and sound between the two configurations is not identical as a Vtwin lopes and bucks irregularly while idling, and the Parallel twin tends to have various RPM where buzz appears and disappears, in my experience, the Vtwin stays pretty much the same vibration at all RPM ranges.
Thank you for this incredible video. Upon watching the F9 video, I was annoyed because I couldn't find anything substantiating their claims and honestly couldn't make sense of it because my last lecture on engine balance is a few years back. Something about their simple geometrical explanation irked me, and you explained how it actually works so freaking well. Fantastic stuff.
Thank you. I was wondering about the claim that manufacturing the 285 is more difficult. It didnt sound quite right. But you went even farther to analyze the secondary balance forces. Very insightful. I am not a mathematician but there has to be a formula to calculate the crankshaft offset to achieve minimal secondary balance on a parallel twin.
Love your video's. I sometimes struggle with English as a second language accents, but you come through clear as a bell! The graphics are excellent. They are simple and not cluttered, and perfectly illustrate the subjects.
Getting called out by D4A is like getting Eminem to rap about you
Yew! What a horrid thought. I would definitely prefer that Eminem not rap about me. Or anything else, for that matter.
Eminem is the workshop.
D4D is machine gun kelly.
It's like McNally abusing your lock.
IYKYK.
@@Fightre_Flighte I mean not really, cause if D4A calling you out means you have to have some idea what you're doing, where McNally abusing your lock probably means you're masterlock and that doesn't *really* have the same implication.
@@carlosandleonwhat
Thank you very much. I said to a friend that I didn't believe a fair bit of what F9 said, but I'm incapable of explaining why! You're a real genius.
13:49 The Rotax 652 single cylinder engine in my motorcycle has two balancer shafts regardless of space and weight constraints... 🤔 It's a pretty smooth thumper, I should add.
got aprilia 650 with rotax that thing is unscrewing its self if you going over 5k rpm's
@@xrhst0s2114 You mean the Aprilia Pegaso? Same engine, just carbureted. Mine (in a BMW F 650 CS) is relatively smooth until 6500 rpm, a bit viby in the right foot peg.
@@StephanKusch Yes I'm talking about pegaso i think it's worse with injection cause you get more power so more dorces literally I screw to spec all the bike except engine after like 2 months of riding
I have one and discovered that if I sit in exactly the right place at a certain speed it blurs my vision. It's the only thumper I've owned so I'll take your word for it. It vibrates less than a CX500, at least.
Hi @StephanKusch , i can't find the second balancing shaft, where is it?
I dont think ive ever skipped your engine balance explanations, even though I have already seen you explain it before. You do such a great job and tweak the lesson each time to fit the video, so its always valuable
Man so glad u responded to this. I read somewhere that the KTM parallel twins are not arrenged 90 degrees apart but ruther 75 deg apart. This was to mimic the big brother motor used in the super dukes and super adv. So maybe KTM they want to maintain sound/signature throughout their models.
I''m with you on that ... I think KTM did 285 instead of 270 to make it sound as similar as possible to their 75-degree (with balance shaft...) V-twin engine. Mechanically, I think 270 would be "better" (as D4A so very well explains) but 285 is "close enough" and let them keep the sound as close as possible.
I learned about forging in class not long ago, and I think that you are right about the need to add a twisting motion in the manufacturing. However is is true that adding an 15° angle would add transverse forces that would not help the two parts of the die align well.
You are so good at explaining these concepts. It's like I can hear my own visual thoughts being spelled out to me! Thank you.
I never get tired of the explanations of primary and secondary balance and even so it is still difficult for me to understand them 100%. I'm looking forward to the video coming to the Spanish channel, maybe it will be easier to understand then.
Thanks once again for your videos.
I have translated this comment with Google, there may be errors.
Google translate aced it!
Glad to see your channel growing, best of luck to you! I remember it was quite smaller not too long ago :). Now we watch it together with my family 😁
You are the Common Sense GURU when it comes to ENGINES !!!! Thank You SO MUCH for YOUR KNOWLEDGE !!!!!!!!!!!!!!
Thanks for keeping it real D4A🙂👌
I like the F9 video channel, but the 285 crank video looked to me to be a KTM ad.
Eh when Ryan himself says you're gonna pay for the difference I'm not sure thats what a manufacturer would like someone to say
I have noticed that on a lot of the content creators this seems to be the case or they have personal bias of one brand over another. I was raised in a Chevy dealership and I couldn't be very objective if I was comparing other brands back in the day.
What's more likely is the deflating balloon of the F9 fans and the rage that follows.
I have nothing against Ryan. I just think a channel with their production slickness will box itself into corners from time to time, as fans mistake slickness of production with objective fact.
@@Ramonatho
But the KTM faithful do it and don't even think about it.
They pay more believing them to be superior, forgetting that many of the bikes are now made in India or China 🙂
I don't even think he owns a KTM
A great, humble, backed by facts to showcase this without trying to discredit someone else’s work by explaining each point logically. Well done.
like your approach and politeness
That's a person with true passion - dropping everything they do and making a calm, profesional video help viewers understand better something they've seen on another channel. Thank you for staying true to what you do.
as a CNC machinist with 15 years jobs on shoulders at many levels, i can say you dont TWIST a forged piece
you just build another die for make a different piece at a "irrelevant" price (maybe 50k-100k euros)
and CNC machines for work on forged pieces can just reprogrammed at different degrees of work with few hours ^^
basically there is no additional costs for make similar pieces because all pieces need those costs
285 or 270 cost the same and if there is a difference is minimal and can be nullified by market selling
another topis is about protos, when you make 1 engine and thats it
there is no selling so only costs
This bothered me too. Start with a different part. Cut a different cam lobe for the crank grinder.
Interesting, thank you for the explanation. Honda Transalp 750 engine also has two balancing shafts, " Primary drive gear can serve as a balancer drive gear for both front and rear to reduce weight and size. The 270-degree crank was adopted to cancel the secondary oscillation. Thanks to this application, even though the basic arrangement includes one weight for the light and compact front balancer and another for the rear balancer, the primary vibrations and force couple can be cancelled with ingenious efforts made to the layout and orientation."
I like watching you explain balance every single time because you constantly explain and update it better. Big engine enthusiast, enjoys your videos a whole lot.
Never skipped the engine balance ibtroduction once, I just can't get enough of your brilliant presentations!
I’m embarrassed that fort got no disagreements in their comments. We’re all sheep. Lesson learned here kids in all things: we always might be wrong, don’t ever let the nicely packaged stuff pass as gospel. Take the time and respect those who fiercely question conclusions and be aware of those who ostracize the doubters, as if they’re hiding from truth.
Sheep? How the f are we supposed to know? Most of us don't give a F in the first place
Just found your video because something about the Fortnine explaination of 285° didn’t sit right. Amazing content, thank you!
Dear D4A, I think you are quite right. I do not know anything about your academic and scientific background and I sometimes miss numbers, equations and functions, and calculus and all those beautiful engineering stuf in your channel. However I admit that those things may be boring depending on the subject and the audience. Anyway, I will try to do the math and let you know in the comments whether or not there is any chance of you being incorrect in some minor details - I just need to model the piston movement and take the first (velocity) and second (acceleration/force) derivatives. And, before I forget, thank you for yet another amazing content.
Do it, you will notice an interesting (but minor) simplification done in velocity/acceleration equations.
@@kwahoo5746 I suspect that the length of the rod plays some role and is being neglected and fixed at an arbitrary number in order to obtain those magic 75 degrees as the moment of peak velocity.
@@fmpinto Yes, this is true. But there are other interesting things (tip: simplification with the Taylor series expansion) to find...
@@kwahoo5746 Thanks! I am not sure if I will be able to follow you that deeply, but In fact the secondary movement got complicated very quickly. Some simplifications are tempting or unavoidable to take me somewhere.
I just now realized I never subscribed to this channel. I've been watching for years, the videos always just appeared in my youtube front page and I didn't think anything of it. It is now corrected
Same. IDK if there is facepalm emoji, but I wouldn't even know how to use it. Still I feel a bit daft.
You made me doubt myself but upon further inspection, thankfully I don’t need correction.
@@AnubisTheSonOfRa I personally do feel like I was subscribed at some point. It wouldn't be a first time YT cancelled subscription without consent or notification. But I'm not 100% certain with this channel.
TH-cam unsubscribed me from a lot of channels 3-5 years ago, maybe they're still doing that and you're actually subscribed already
@@justinedzard i think it's possible, but I'm still subscribed to some Minecraft channels I haven't watched in 10 years so I doubt that's the case
Very well and clear explained. That and your respect towards Fortnine shows you not only in the know but also a decent human. Actually, I accompanied a project at a crankshaft maker for three years. We set up a complete turnkey crankshaft production line and during that time I learned and saw a lot. I am no technician but still I don’t think that production of a 285 cs should be more expensive than a 270 cs. The tools within the press as well as the necessary procedures before and after the actual forging should be (nearly?) the same. At least costwise it could be neglected.
I love watching your explanation of engine balance slowly get refined more and more each time you talk about it
This is a very detailed but easy to understand and follow description of the way the different forces balance out-so well done sir. I have some limited experience of this having spent some time making 360, 180, and 270 degree parallel twin cylinder crankshafts-and balancing them on a computerised Schenck balancer. The crankshaft were all machined from solid using EN30B grade nitriding steel, and were in the main for Nourish/Weslake 8 valve twins of various capacities.
That sounds really 'fun', envious you got to make them.
I've had to 'make do' with re-phasing Yamaha XS650's as I can't afford a Triumph plus all the parts to go with it.
I'm so glad you've been educating yourself & passing on that knowledge
Otherwise not knowing no better I'd've taken F9 on his word commiting myself a disservice
Reading the title of this I initially dismissed the video thinking that intents to get clicks just by arguing against F9 , I m happy that I saw it now, you did a true and detailed peer review here, mad respect for the effort!! Needless to say your arguments are all compelling.As a scientist I am truly pleased to witness such high quality of debate in a medium that things can easily go astray..
Ryan’s pants are down now - what will he do? A response video? A counter video? WATCH THIS SPACE - D4A throws down with F9!
Fortnine is often 'trust me bro', it's format isn't conducive to deep dive explanations like D4A routinely puts out. I subscribe to both.
ok dont piss your knickers
Great article again, gave me a lot of pleasure watching it.
In a 360 or 180 vertical twin, where both the pistons stop simultaneously, the flywheel must use energy to get them moving again, but this is not so in the case of the 90 and even better the 76 crankshaft when one piston is at top dead centre while the other (76) is moving at maximum velocity. However;
The ideal off set angle of the crankshaft where the second piston is at maximum speed is depending on the ratio of connecting rod length to crank radius.
F.I. If the connecting rod would have an infinite length there would be no secondary imbalance or secodary piston speed.
I am so happy that i ride a KLR650S and not having to worry about any of this.
i love having 40 hp
A single cylinder intrinsically has more vibration than a twin or four.
@@stevejones1318 Yes, but a great deal less problems. My 650S is 100 pounds heavier then 2nd gen KLRs. Mostly from rubber mounts. It has little to no vibration until you get to 70mph.
From which; where i live it's a rarity to get to 70mph.
As a total ignoramus concerning the fine details of ICE technology who chanced on this because the algorithm/leprechauns thought I needed a change of life focus (?), I have to say thanks for the new info and I am *hugely* impressed by the clarity, enthusiasm, and fair mindedness of this presentation. The diagrams were particularly useful. Excellent work!
The moment I saw Fortnine's video, I knew this one was coming. There's no way you would leave a engine balance topic out in the woods. Nice work (and I like Fortnine too, awesome channel)
I might be wrong but after a quick calculations it seems that the highest acceleration point depends on the ration between crankshaft radius and connecting rod length. The smaller the radius and the longer the rod then the max acceleration point is closer to the 90 degrees. The minimum seems to be around 64 degree when the ratio between crankshaft radius and connecting rod length is somewhere close to 70% - 86%. The mentioned 75 degree is correct only when ratio is around 30% (so the rod has to be about 3 times longer than the radius). By the way, I love D4A videos and I'm his big fan. Keep the good work D4A!
Yes, d4a should say "about 75 deg, depending on crank radius to conrod length ratio", since all small (motorcycle/car) engines are around 30%. According to S. Luft "Podstawy budowy silników" the ratio is: SI engines: 0.25 - 0.28 (inline) and 0.27 - 0.3 (V), diesels: 0.24-0.3 (inline) and 0.27 - 0.3 (V).
I was expecting such an answer - just was too lazy to check😅 Thanks!!
Your explanations are brilliant. I came to this channel with the most basic understanding of how engines work, but learn a lot from every video, and find them all fascinating. My respect for mechanical engineers has also increased massively. Also love your to communicate the complex, in understandable terms, and with humility.
Been a follower of F9 since day 1, I admire your utmost professionalism and honesty towards one another. 👌👍
Keep it up.
I suspect KTM does the 285° inline twin to more closely match the character of their 75° V-twin, which I assume they do because it packages better than 90°.
Exactly right, man. Consistent sound signature. Like Harleys signature sound, only the KTM sounds much better, to me...
yes thats the reason.
I've checked their marketing material and they dont claim to have better balances in their engines. so its completely a matter of preference.
I’d love to see a video of this guy and Ryan just talking engines. Top tier lunchtime viewing content
As soon as I watched that Fortnine video, I was sure D4A will come to the rescue because I smelled bullshit. He didn't give explanations, just claims without evidence and also that forging process becoming expensive because of an extra twist seemed very under researched. Thank you D4A and kwahoo_archive
Sticking with “facts” is why Driving 4 Answers is such an awesome channel.
And your respect of other TH-camrs is commendable. It was not a case of the other person being wrong…, rather just incorrect.!
10 out of 10.
Semantics.
Twisting a crankshaft after forging has no additional significant cost associated with it, even more so if the price charged is premium.
I had to call up a friend working at the Bajaj/KTM/husqvarna factory to verify this.
While the factory he works at doesn't manufacture KTM's over 490cc , He worked in Spain factory before with larger engines. Here is the direct text from him " Balancer is in all engines from 250. Brand goes for that few percent of performance so used 285. Bigger ones use V twins and sell more. Cranks are made with same machine for 790 and 1200. dye is different thats all"
Original text was in native language and I translated it so grammar is not right.
... and "dye" is misspelled (in this context); Dye (noun) is a substance that imparts color; die (noun) is a tool for imparting a specific shape to a material.
This guy can put his content behind paywall sort of like a Master Class and yet he's doing it for free. Absolute Legend!
Acceleration of the rod also contributes to force. This rod force has components both parallel and normal to the stroke. The crank exerts a force normal to the stroke, as well as along the direction of the stroke. If I get ambitious I might work out the rod force, along with the piston and crank force, vs. time.
Thx, I was always asking myself why everybody speaks only about piston forces and nobody speaks about the conrod forces. Are they so small that they are neglected ?
@@gsbeak About (IIRC) 1/3 of the conrod mass is considered as a mass moving linearly with the piston and about 2/3 as moving circularly with crankshaft journal. The mass in linear movement is added to the piston mass, and the mass in circular movement can be balanced with crankshaft counterweights.
Thanks for your response. The 1/3rd 2/3rd approximation is very useful to know.
The motion of every point in the rod can in principle be calculated, and the effect of that point’s mass can thus be calculated. The overall sum of those forces can be calculated, too.
Though I use finite element analysis tools, the ones I use are for electromagnetic field problems. So if I were to undertake such an analysis it’d be pretty crude. But the tools for the mechanical analysis definitely exist.
I might suppose the con rod lateral forces are quite closely related to the inline piston forces. Just a guess, though.
@@maxenielsen I think, this can be done even easier, without FEA, since we can consider the conrod as a rigid body.
Calculate the center of mass, and the moment of inertia. Then multiply them by linear and angular acceleration respectively to get force and torque.
This sounds like an interesting exercise, with a small help of CAD tools to estimate conrod properties...
@kwajoo5746
Yep, I agree that FEA IDT necessary because, as you say, the con rod can be described by its center of mass and moment of inertia.
It’s interesting to think about the torques applied by the crank and wrist pin.
Thanks for your comment.
Very interesting. I didn't understand any of it, but watching FortNine's video almost had me trading my "plebian Yamaha" for a KTM. What a fool I would have been!
That low frame rate is a sign that you had to get this out as fast as possible so people wouldn't be misled. I appreciate that dedication. I'd like to add that regardless of whether or not Ryan is wrong about 285s, I still prefer them. I find that they sound better to me, with the 270s still having just a hint of that nasty 180 sound at high RPM. The next best one is the 60/300 degree twin, but that can sound too much like a cruiser at times to be in a sport bike, IMO. Still leaps and bounds better than Harley's sound, though.
The Harley 'potato-potato' is due entirely to the crappy intake they have and 'charge robbing' at low rpm on carburated bikes.
The fuel injected bikes deliberately mis-manage system at idle to replicate the sound.
HD spent over ten years trying to sue Japanese cruiser manufacturers as they 'patented' the HD sound
@@1crazypj Dafuq? Do you have a video of a non-potato Harley idle (besides the 60-degree Vrod)??
@@Drunken_Hamster Nope, I was teaching Suzuki F.A.S.T. but spent a lot of spare time over at HD which is why I know about it.
I forget if it was 2007 or maybe 08?
I attended several HD lectures over 2 years, but, being Suzuki, couldn't, take the HD factory tests
It was when fuel injection was available but most bikes still had carbs (maybe FI was optional?, I forget)
I probably have paperwork on it somewhere safe, still fixing things from Hurricane Ian in Sept 2022 with a lot still in boxe.,
MMI wanted instructors to get as much knowledge as possible, majority of import instructors had less than zero interest in Harley but I always want to know more. Had a few good friends there who really liked discussing differences between USA market and European/British market. (plus a few A-holes who wouldn't speak to me 🤣 😇)
One Cajun instructor asked me to bring a translator (he was a right dick who got canned for telling a female student she should be 'at kitchen sink, barefoot and pregnant')
I've said it before, I'll say it again - I LOVE this channel!!! Brilliant explanations and a fabulous, engaging presentation style. Thank you 😊
Congrats on the 1mil sub, D4A!
Even knowing about engine balance (or imbalance).I always watch your explanations over and over. Your are awesome. Thank you.
I agree with balance. Let's look at torque production. More importantly let's look at how the firing order is striking the tire. Does the tire have a recovery time from ignition shock?
Another well made video.
Yamaha's big deal with the cross-plane-crank R1 involved the rotation speed of the crank being more uniform because it never had all pistons starting and stopping together the way a conventional inline-4 has it. Off the cuff I'm thinking the 270 twin will be closer to achieving this than a 285 twin, and this was only briefly touched on in this video, but the math starts getting really hard! The uneven-firing-pattern and tire-recovery situation seen in MotoGP is a whole 'nother situation on top of this, the ever-so-vague "rider feel" playing a part, with the current (known) interesting best example being the Ducati 90-degree V4 with 70-degree-offset crankpins.
This was a beauifully simple explanation to something that is much more complicated than I initially thought it would be.
Thanks for taking the time to create, edit, and share
Thank you very much for making this video. I spotted the mistake in the video immediately, but I do not have a TH-cam channel to discuss it. Fortnite has mistakes in almost every video as well as "engineering explained".
That's why I stopped watching F9 video's, too much opinion instead of facts
I enjoy your video's very much but as with F9's video I say, "Pffft. Husqvarna's Nuda 900 model, designed & manufactured under BMW ownership, had _the_ best version of any of the modern parallel twin variants.
They took the Rotax manufactured 798cc BMW engine from the GS800 and increased the bore & stroke by 2 & 5.4mm for a total of 898cc. They then offset the firing order to 315° from 0. Husky took a characterless, _agricultural_ sounding engine and gave it more character than the Toy Story and Shrek cast combined.
It sounded amazing, the bike looked hilarious and it was enormous fun. When I added a Remus slip-on, unbelievably, it sounded even gnarlier (baffle almost always in - I'm not a monster!) In fact it sounded so good it received as many looks as a mates Diavel.
Apologies for the lengthy post. I wrote something similar in the F9 video's comments and it was completely ignored. Only ~3,500 Nuda's were built (incl., the R variant) and this bike was just cool enough it shouldn't be forgotten 🤘
I looked for a comment about the Nuda. An amazing piece of italian engineering (Husqvarna was based in italy under the BMw ownership), it sounded like an Harley (same firing intervals of a 45° V Twin) on crack.
Both the frame and the engine are the outcome of the italian passion as the red heads of the cylinders (trademark of the Italian Husky engines, see AJP pr7 monocylinder) prove.
I often dream about getting myself a 800 gs and upgrading the engine like it was in the nuda. Its a dream bike but maybe too raw and focused on beeing fun that it could catch on for its price. its similar with the hypermotard and other twin bikes trying to be fun bikes for of all and only secondary useable as a daily.
Fortnine needs to focus more on quality videos again, this is the third "Fortnine is wrong" genre video I've seen in the last few weeks.
Wait what?
@@d4ayes, something has changed with them. They make more and worse videos now. Also new (not very good) presenters are with them now
@@d4a yes, Spite's corner did a video that's not directly saying Fortnine is wrong, but that some of their research videos, made with sample size of 1-2, has been taken by novice riders as gospel. Example includes their engine oil analysis during engine break-in of different brands. I forget the other example but I am sure it had to do with a quick repair hack type video.
@@manitoba-op4jx you're right actually, but that's their niche. Completely new riders getting the hang of new terms. Its like an "Introduction to Motorcycling" sort of channel with outstanding production value.
Of course every rider should do more research after the introductory videos from Fortnine.
@SMTahmid they specifically point out that the sample size in that experiment was tiny.
You can't fault a creator for the generally statistics illiterate youtube audience.
Awesome video. As for KTM choosing a 285 interval, it's important to remember that their V-twins use a 75-dgree spacing (IIRC, some of the engineers who designed the original RC8 engine were originally responsible for designing the Rotax 60-degree V-twin used by Aprilia, and they incorporated the lessons learned there in designing the KTM engine, namely spreading out the cylinder to reduce interference at BDC, while being more compact than a 90-degree set-up). In designing the LC8, choosing a 285 crank allowed them to keep the same sound signature as the LC8 (also gave them a certain uniqueness)
Ah the desgined duel of the fates: the Physicist and the Mechanical Engineer!!!!
Bosnia Herzegovina vs Canada!
This dude is bosnian? I never knew where his accent came from.
I think Ryan once said something along the lines of "The physicist wants to move weight, and the mechanical engineer goes 'oh fuck'".
And we need someone who does testing to step in and instrument both types of engine and see how the real world compares against the two sides of the debate.
“This is absolutely minimal but quantifiable.” Best sentence I’ve heard all week.
Great video - more engineering, less hype! I have an '06 Honda crf450x (single cylinder) with a single balance shaft, which holds vibration down to an acceptable level for riding offroad. Because this engine has low rotational inertia, it will rev scary fast.
When it comes to engines, everything is a compromise; off road applications favor weight reduction, while on road favors smoothness.
So you missed my comment to Fortnines video? 😉 I corrected the Fortnine video in my comment, and also added the historical reason presented by KTM!
As you guess - it IS a sound/character thing, not an attempt to minimise vibrations.
I’m pretty sure that most engineers reacted to the videos erroneous claims, but youtube-viewers don’t always point out wrongs they see, even if they are engineers. We are not all difficult, just… you and me. ☺️
Just excellent - took a lot of guts to 'review' Ryans vid, but so refreshing that someone did without making it personal. I am a fan of both as I think both are very good teachers.
Babe wake up, the 20th explanation of secondary balance by d4a just dropped
I wouldn’t know if you were right or wrong, but you explained things in a way I and others could easily follow and have a reasonable idea of what to look for in reference to not only these engines but many others. Good job.