Was this IT? Road to Most Powerful Two Stroke
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Hey man, i’ve made hundreds of pipes for 2-strokes id suggest using backing gas next time! Will get rid of a lot of blowouts and result in a smoother weld on the inside.. And a way more neat weld outside :) love it how i was screaming at the videos a couple of months back “ITS THE PIPE” but i knew you’d probably never see the comment.. Hope you see this one tho!
Anyone who has welded stainless would know how important backing gas is.
Also I'm not sure if he is using a foot pedal. It made a HUGE difference for me in welding school back in 1982. It's a must. I bet that is one of the issues on his welding if he don't have one.
I'm a retired certified millwright but I also have a basic welding ticket.
pretty sure it doesnt matter in his application@@canadianoddy8504
Even mild steel welding a lot better with backing gas. Putting a peace of copper behind the welding helpt the result.
No need for purging with welding mild steel. Just correct amperage and gun speed.
agree@@GlobalSLO
I’m a little worried that your dyno may not be recording horsepower correctly. She sounds good, maybe try a friends bike that was tested on a commercial dyno to compare results??
Too, in last Vid i thought that he actually did it. For me it sounded really well...
I think so too. Think about how often things changed during process and how many things went bad iver time, this could pappen tonthis self made dino too. I understand that the dino is not the Target of this orogress but it could be a restricting factor
Back when I was young I had 3 dirt bikes I would ride on the same day. Started with the YZ490 then when I was beat up enough jump on the YZ250. Would finish the day with a Suzuki 125 to just put around. I can tell the sounds of a good 2 stroke.
As long as rpm is reading correctly and the weight of the roller is correctly calibrated the hp should be correct. Maybe recalibrate after multiple runs with close hp figures and see if it changes.
last vid was almost on the pipe for me. almost
Others have mentioned aspects of dyno loss - here's a summary of what I see:
1) 3+hp lost at high rpm after you pull the clutch - that's JUST the transmission, chain, rear axle, and tire/roller interface, not the belt drive
2) Loss in a transmission/driveline has multiple factors, one of them is torque dependent due to the friction in the gear teeth and bearings/bushings. Force vector on a gear tooth is the same as on the bushing/bearing, but the torque loss can be higher due to the bigger radius of application (depends on level of gear tooth friction relative to bearing/bushing friction). You don't see realistic torque-dependent loss during a spin down, so factor #1 above is an underestimate of the loss when you're full throttle. Hard to estimate, but let's guess additional 1hp lost due to torque through the drivetrain.
3) Inertia of the roller is accounted for, but what about inertia of the wheel/tire? Some additional loss here, but probably pretty small, I'll ignore it.
4) BELT DRIVE: who knows? try to measure it! Belt with an idler with significant tension will have some real torque loss, when you consider you're about 4-5Nm at the crank, and that the torque loss in the belt is constant (or maybe even rising) with rpm, that can be a big hp killer! Maybe 20% there alone, so potentially another 3hp!
5) I thought I had one more item, but can't remember - I'll add a comment if I can think of it.
So, in total, you could be losing something like 7hp total, so you may already be looking at closer to 18-19hp at the crank already.
Also, subjectively, the last runs with the bigger stinger, the last 2000rpm or so are happening FAST!!! I think you're making a lot of power just before you hit the wall, and the wall hits too soon. I think you're getting really close!
Nice guess. But he needs a dedicated engine dynamometer to eliminate all of the other crap.
@@davidgierke7582he has one. He also has an interial dyno that works great, so in the interest of chasing one bone at a time, he’s using it.
I've said it before, but I think he should go back the old dyno bench with load cell, but change the truck break for a hydraulic pump. It's simple and doesn't have a bunch of maybes and ifs. Swedish Tvåtaktsmeken has used a really nice one a long time and has made another reasently with some improvements.
th-cam.com/video/24RMh4JUuZM/w-d-xo.html
All guesses aside - he did mention two videos back that on the same dyno, his 80cc metrakit AM6 delivers 13hp, so in any case he has the same power with all the transmission losses as a quite potent 80cc! But to me 13hp from a nicely tuned 80cc am6 is much too low numbers..? Reading some forums it seems that this kind of setup should make at least 15.5-16 hp, but probably more. Hell, most 70cc make about 15.5 hp!
This is an assumption, but if this assumption is correct, and the 50cc is making the same power, that's not bad at all.
Finally someone who knows that rundown is not realistic loss. Usually when I mentioned that to some dyno operators (people who just have dyno), they start fuming haha.
I have given you my advice already, but maybe with the number of comments you did not notice yet. Run a couple of curves with different fixed ignition values. Take the best run for each ignition value and put them together in one diagram. Then you will see, which engine speed needs which spark and you have your new curve, that should be validated in a final run....
it is a great idea for fine tuning, but at this point, there is an issue with the engine that prevent it from getting its full power. So this should be adressed first and that's what he is trying to do.
I find great assurance when your constantly making 3 steps forward and 2.5 steps back. Whenever I take on a project it goes exactly the way yours does. Thank you for sharing the pain and success.
The exhaust gasses are exiting the cylinder exhaust port at supersonic speed AFAIK. It appears the abrupt shape change in the ex port to pipe adapter could be reflecting a large amount of spent gasses back into the cylinder at very high velocity thus completely disrupting the much slower moving intake charge distribution and exchange within the cyl. This would disrupt cyl scavenging in a massive way if my idea is sound. Just throwing out my thoughts upon a very brief view of the part I'm discussing.
Based on my understanding, "line of sight" needs to be applied to your exhaust port to pipe adapter to reduce the tendency of wave reflection off a great deal of the cylinder ex port area. The functional area may be reduced to the "line of sight" from the pipe side looking into your adaptor.
Hello
I come from Germany and am following your shipments with interest. I find you very brave to keep going after disappointments. Yes, 50cc is interesting. There already is
50ccm with 20hp. So keep going, you can do it.
I don't have any idea on two strokes so take this with a grain of salt, but I'm studying musical composition, and we have acustic related subjects. What if the actual resonance of the pipe hits the initial power band at arround 11000rmp and what you are seing at almost double that is an harmonic of that resonance? It would make sense since when you get past that point the pulses just inmidiatly die.
bang on Adrian. 2 stroke pipes are all about resonance. The stronger the pulses the shorter the resonance period.
What gets complicated is balancing the resonance to the temperature, the speed of sound and therefore the resonance change with the temperature and the temperature depends on how well tuned the engine is along with how well the pipe is doing it's job.
2 stroke balancing act.
Look into an S shaped expansion chamber. When i switched to that type, the power gains were extremely higher than conventional straight expansion chamber. 100%
2-taktere er som en religion. Er så glad for å få være med på reisen! Du gjør en kjempegod jobb, både filmatisk og mekanisk. Heier på deg!
Some good results Alex, in the right direction too.
As I've said I'm a boilermaker/welder, here's a tip when tig welding what you are with the new exhausts, you need to purge with the gas your tigging with, the internal side of what your tigging, use some light plate steel as end cover's for pipe sections, with a hole for a gas line, use tape to hold in place is good enough, doesn't have to be sealed totally, you don't need a lot of gas flow and not more than your using to tig with, just as long as there's gas there and not atmosphere air that contaminats the weld from behind, it will help flatten your internal weld faces, without purging, the weld face can have built up dags and lumps which would create little pulse wave echoes disturbing the pulse action, it'll also help a little with blow through too, that's because both side's of weld are shielded and no contamination from behind affecting the weld as you go, where as when your welding like you are, there's only one side that's shielded, I hope that makes sense mate.
Required:- Telescopic centre section of expansion chamber + Adjustable Iris style stinger.
FYI if your carburetor is flattening out on the flow meter then you will not get any more RPM or peak horsepower out of it at any rpm
I really like the wide angle recording. I always watch YT in theater mode, so it's just really awesome to get that extra video around the edges. It's the little things like this that make me happy.
:)
Try cutting open a commercially available exhaust pipe. A lot of them have a baffle were the straight pipe transitions to the expansion chamber to redirect the waves so they are not directly aligned with the inlet flow.
I put out a short video last week of the Northern Lights while I was visiting Norway. Lovely country by the way, despite being -12c. In that short I speculate that the Northern Lights is actually caused by unburnt 2T oil, so as this correlates with the timing of our dyno runs I guess the lower EGT is something to look at next! Great work Alex, keep it up, we're all behind you!
For dealing with kart engines an unspeakable amount of years: If you want higher temps less fuel would do it. At least on our 2 strokes (60-125cc) that would do it. Then again, if you had a taller gear it would strain for longer and push temps.
love it spent years in karts. Yeah EGT is the real mixture test. Ran 100cc piston port and reed at 1.1K at the end of the straight then would choke the f out of it and pull 600Deg of the piston temp under brakes. Mychron2 warning light set to 1.12K any higher would seize, if it got there then more high jet. Used head temp (air cooled) at 85Deg (from memory 15 years ago) and set low jet by it. My probes that he is using and they are top quality and spot on accurate for K Type. Made by Temperature Controls in Sefton Sydney with special clear high temp outer coating to stop the copper braid from degrading from the insane vibration up to 19K rpm. Plug always white back at the pits but it never locked doing this - was running 50:1 synthetic oil on 98 Octane
I think maybe the term you are looking for is "standing wave" this is what they call the captured shockwave in the intake of super sonic jets to slow down the air to sub sonic speed before it hits the jet compressor blades. If you have one of those developing in you tail pipe that would definitely cause a breakdown of the pulses you want.
I think me and a few others noticed 5-10 episodes back that it really needed a fresh properly designed pipe as the hacking and bodging of other stuff just wasn't working with it. I think the key is you realized all the geometry "errors" you made during the design of the cylinder and that let you design the correct pipe this time. Glad to see it responding well to that!
Just a thought: The lower EGT means the speed of sound is lower, thus your shorter pipe will be targeting an even higher rpm than you designed it for, unless you're taking the lower EGT into account when doing your design.
Edit: I see you touched on this in your outro, I jumped the gun a bit on this comment hahaha
3:30: when forming cylinders and other shapes, bend the ends slightly more than they need to be. when you get to join the ends together it's MUCH easier to reduce an over-bend, than it is to bend the ends inwards. (if you see what i mean - sorta tricky to explain..)
Hey Brother , I used to build pipes for several expansion chamber companies , J&R, T&M Eng, S&S headers, FMF ,and DG . I have never seen such a small diameter stinger on such a small motor but I think you know what you are doing . It sounds great .
That is right and personally i think the stinger should have a lenght at least 5x of the initial exhaust diameter, so that it can build a more precise wave, otherwise it's gonna get messy
My KTM 380 MXC has a stinger ID of 1.13"...it flies down the track nice...
It sounds like another chapter can be started...
Sort out the gas tank...take your 12.5 HP Aprilla...out for a spin...
You know your approximate weight....the bike could be weighed...
Run down a 1/4 mile the get an ET...
Maybe it will do the quarter mile in 12 secs at 99 mph....
Then a HP calculation can be done
Good job getting her to run this good
My daughters KTM 50 has an SXS pipe on it. Very hard to get that pipe these days. It's got a 16mm stinger. I had to scratch build a muffler for it since it's so much smaller than stock. The stinger is a LOT longer on that pipe compared to what has been made here.
I need to get you to repair my silencing can on my kart pipe.
@@bkh5746 hey brother I would be happy to do that for you but I don’t have a torches or any of the tools I need to do that anymore I wish I did you should be able to just buy a piece of mild steel tubing the desire you want and cut the old one off with a hacksaw I’m just have somebody will the new one on
Greetings from Finland, love your videos. They are a true inspiration. For sheet metal joints I often use Silicon Bronze (CuSi) tig wire. It doesn't make boogers inside the joint and it's gas tight.🙂
The madness will probably never end
It won’t
I imagine he would over engineer a ham and cheese sandwich
I hope it doesn't
I remember Back in the early 90 s F1 powerboat racing (Heavy tuned 2 stroke Methanol) they worked with spacer- rings on the sparkplugs to make it run good , just want to say it could make difference.
Its nearly impossible to guess pipe temps in the sim until you test in real world. Makes sim pipe development hard
You can model this probably close by lowering pipe temp in the sim to match rpm points
you will find that its hard to make power at low bulk pipe temps
as power increases the temp goes up - so chicken and the egg…
I also think you need a stinger outlet tube - it can play a nice role in tuning
I agree. Build a bunch of pipes, dyno them, sim them, dyno them, sim them. Give up on the sim for a while because you don’t trust it, go back to the sim because you are second guessing yourself not trusting it.
Watching you build an expansion chamber from scratch reminds me of 1970 when my friend Tommy Joe built his own expansion chamber using plans from motorcycle magazine.he. made mandrells on a wood lathe out of oak wood. This was on a 1970 125cc Yamaha Enduro.
It worked really well. He is an excellent gas welder.
I was thinking about this some. Make sure you always set that EGT at exactly the same distance from the piston face over your iterations. It will skew your data if you don't.
Nice!!!! You may want to consider "back purging" while welding the pipes. (Flowing shielding gas inside the pipe to prevent internal oxidation) May help with your issues. My TIG welding is horrible, so it is just a suggestion.
Please familiarize yourself with “Taguchi excitement design”. It’s a simple engineering test that shows you which variables are important, how important they are, how they interact with each other, and where they should be set at.
It’s pretty easy to setup and it’d keep you from chasing a sea of variables that all affect each other in seemingly random ways.
I’d start with running a Taguchi L8 on 3-4 variables with your pipes.
first I learned of this,
seems very powerful
thank you
The exhaust manifold length/shape matters a lot on smokers.
I had the DG pipes (and ported heads) on my RD400. Loved them and hated them. Loved the power, hated the droning and loud sound while on a long ride. Plus, they garnered a LOT of unnecessary attention. They absolutely worked. They were longer than the stock Yammie pipes, so there's something to be said for length too. I remember Team Yammie and Suzuki running very long chambers on their RGs etc back in the 70s and 80s.
Best thing I ever did to my RD400C was find some stock pipes and stock airbox and put them on. I can not believe how much more torque the damn thing made off idle and into mid rpm.. exactly where youd need it when bombing around town. Luckily my cylinders had never been ported. Also, the dg's and pod filter was so insanely loud and that DRONE it made was mind numbing.. I dont miss them at all. The bike has become such a pleasure to take out on the weekends now, I love it. Something i can do now is leave it in 6th and slow right down for a corner then just feed in some throttle and the bike just pulls with no complaints. I could never do that the with pipes and pod filter.
I remember my chum's RD400; a real basket-case, but had standard pipes; As the revs climbed and it came into the power, it just lifted the front wheel so smoothly. Sounded so good - without the attention-grabbing Micron's on my RD125 twin.
Here in England 🇬🇧 we soon discovered that even at a high rate of tuning and porting the standard Chambers gave best all round power.
@@ianmangham4570 Like a ""FACTORY PIPE"" doesn't get HOURS & HOURS of R&D & should work the best. I NEVER could understand the ""MIX & NOT MATCH"" toss it up on the wall & see if it sticks, hap-hazard garage hop-ups that just seemed to create totally un-ridable, LOUD & horrid bikes, most of the time after spending half again the cost of the STOCK BIKE, trashing all the STOCK PARTS & ending up with DOO-DOO!!!
The gas is faster than the sound
Awesome job on the pipe, your best welds happen when you are most comfortable, use a clamp or block to help position your torch hand. Been watching for a long time, thanks for bringing us along!
I had a RM 125 1986. I did shorten the expansion chamber according to mx action magazine to make a rocket pipe. I got a shorter poweband more power higher up in the rev range.
Nice to see the "tuning" has finally started!! ..I have a really good feeling about your progress! ..I have a good "ear" for engines and I do believe there is a good "jump" in power coming..I'm so happy for you!...👍👍👍🗽🇺🇸
Just a dumb thought have you double checked your setup on the dyno. Could wrong ratios in the setup cause off results. Love watching your videos and see how your mind works.
I thought the same. If the rpm is still not calculated correctly by the dyno it could also explain why the timing curve does not work as well as it should.
@@bomberjuli dyno is based on weight and rotation+radius?
@@bomberjuli The amount of rpm he is getting it seems like it should be making more horsepower. That or the motor is barely making any torque.
A 50cc, If you can get to rev that high, would be at 20hp or over.
@@richr161revs those not always mean hp
@@alexrodensjo348 Your right, but 17k rpm at 11hp would mean the motor is making less torque than a stock 50cc bike.
HP= Torque+RPM.
Or simply how hard your piston is pushing down and how fast the motor is turning.
I am a retired Welder I used oxygen / acetylene when I repaired my collapsed expansion chambers. Just a welding suggestion, you definitely have the 2 stroke engeering together. The coke bottle is the best explanation ever. I m 73 and still interested in Motorcycles like women... And shouldn't "do" either one....! LOL
You’ve used a lot of cool DIY techniques in this build it would be cool to see you use a pressure washer for hydro forming a pipe.
I feel like some pressure transducers and a picoscope would really guide the development. Could even use in cylinder pressure and ignition trigger comparison to set timing.
Finally got back to 12hp.... I feel like you should run the death bike on the dyno to see if it's reading correctly. Keep up the great work.... 😁👍
PLEASE READ THIS. There's some serious SHAKING on the drive belt right at 17,4xx RPM on EVERY SINGLE high RPM RUN. Example 23:19. You can see it on the previous video as well. Watch on 1/4 speed if you have to. Also I saw multiple instances of a multi thousand rpm jump on the RPM readout. Perhaps that's a valid jump due to the Dyno refresh rate? Or maybe there's something else going on. Slip?
I think that's when he lets of the gas, what do you think? (I've only noticed this one example you've provided.)
@@raycar1165 Impossible to say from this angle, It seems like his clutch hand and throttle hand move at the same time after RPM stops moving. To me it sounded like a WOT soft rev limiter like on a modern car. It just hit a wall of resistance. Maybe it's some sort of harmonic on the belt that suddenly kills torque.
Salut mec !
Pour ton pot
J’ai vu le gars de chez KRM faire les pots au chalumeau
Bon il faut un sacrée coup de main mais c’était ouff la qualité
Il soudait chaque tronçon comme toi
Après il surfaçait les tronçon sur une ponceuse à bande et enfin il les passais sur un cône métallique avec un marteau pour les mettre bien rond
Ensuite il soudait un tronçon à un autre et il le tapait sur une sorte de boule pour que le pot sois bien rond à l’intérieur et pas avec des facettes et ça permet aussi d’aplatir la soudure
Et enfin il soudait le coude à la fin
with a wide exhaust port the area the exiting gas encounters is larger and so that reduces the pressure at the beginning of the exhaust pulse, what is going into the pipe, and that results in less intense return waves for a less effective pipe. And no pipe modification can correct that. So obviously there is a limit to how wide the exhaust port can be made before this problem becomes too much.
Could be the problem 👍
I think you should rework the first third up to the diffuser. In my opinion that is far too big. 28mm starting at the cylinder brings improvement. The exhaust doesn't manage to suck properly
It was made that big to keep pulse intensity at bay, bleed off some energy. No help, seems to be two resonance systems fighting each other in such a short pipe - helmholtz and "normal" pressure waves.
Here is a thought for you to consider. Back in the seventies we were experimenting with making our racing go-kart 2 stroke engine get greater power. We designed the expansion portion of the exhaust pipe (i.e. the portion that is a straight pipe) to mechanically get longer with greater ram's by sliding the one tube inside another by about 50mm. We seemed to have quiet a lot of success. However we could not measure it because we were unable to measure the success. But it certainly made the power band longer.
I used to put a PE exhaust on my RM and that used to work pretty good
@2STROKE STUFFING ALEX.. Here's an idea a friend did MANY years a go while 'Home tuning his Kawasaki AR125... He took a medium sized exhaust that had a wide-ish expansion chamber with a flat cylinder mid section, and then tune it, run it see what power, then, cut the pipe (at the mid section), trim off a 5mm/10mm band, reweld pipe back together (thus shortening the chamber by approx that length, tune the engine to match and see the results. Keep doing this till you find the IDEAL chamber size for the tune you want. My friend Steve did this repetitive job for quite a while with different heads (and modding those heads - back before computers n such, and made some NICE power gains with a decent power band!)...
SO, from a lowly 12BHP AR125 rotary (wasn't the best 125cc bikes compared to the TZR125,NSF/NSR125 & RG125 (which had 'Powervalves etc'), he managed to get up to around 25+BHP with the unrestricted Kawasaki AR125 Kit. Eventually though, he just replaced the motor with the one out of the Kawasaki traily bike the KMX200 and tuned that up instead. 🤔😏 It was a FAST AR, and though his other mates on their NSR125Rs and TZR125Rs thought they were the bees knees, his 'Lowly' Kwak, showed them something or two 👌
😎🇬🇧
You hear the sound of the exhaust, it's not the right sound. When the expansion chamber works optimally, it gets a metallic sound and you don't have that.
A lot of times when misfiring at top RPM range it can be corrected by a 1 step colder plug range! This works for 2 and 4 stroke motors of all types! I have built and raced auto and motorcycle motors since 1968! Multi spark on 2 strokes is just as awesome as 4 strokes for added low end torque!
I really enjoy your videos and your approach of build-test-speculate-modify-retest.
I am also sure you know very well that EngMod2T, as a tool, is able to give you all the insight you need, to explain what is going on with your engine configuration.
Looking forward to watching more videos of building/testing but also hope you will include the EngMod2T insights (port traces, pressure/temperature traces, mach traces, scavenging efficiency, purity, etc etc) that explain the performance that you found on the dyno. Things that work and things that didn’t work (and why they didn’t work)
I think you should test using a proper length stinger. The very short one you are testing with will give way different results to a full length stinger.
It seems like hydroforming a pipe from two sheets welded together with a grease pump would be a lot more efficient for making one-off pipes… there are how-to’s on YT that might be worth looking into.
I've read on the internet that smaller diameter pipe headers increase torque because of the increase in velocity. Also, I heard from a former KTM Racing mechanic from Protugal that bigger diameter pipe, full exhaust, makes more better torque because of the increase airflow but slower velocity. I wonder what is your opinion on this one?
10+ for making Own exhaust bit bigger 👍🏻.
Now only need some more fuel Petrol.
Becase it want too die in high RPM.
So Larger nozzle or petrol needle.
That need too by the Good Key.
That's all as far as I know it should work.
Maybe a different toothing so that it probably works better.
Well done so far 👍🏻
test with 20mm longer header , when your thoughts are correct the powerband should drop 500 RPM earlier.
The production value on this one is amazing! loved the TIG section on the pipe! I love the spigot, the EGT, yeah dude! Also, put a chain guard on that thing, you might be faster with one leg out on the track, but having one leg would suck.
Look at the Thai long tail boats running two strokes at insanely high power levels and high rpm. The pipe is JUST the divergent cone section. No belly, no convergent section.
Hey @2STROKE_STUFFING Just an advice coming from DMT's on films: Always have at least 3 copies of the thing, prefferably on 3 types of medium, geographically separated from each other, which is less important in your case, but having the copies can't hurt. The practice tends to be: Footage get's recorded, downloaded on set, that material is shuttled to the lab, where it gets copied and backed up an other time (now we have the footage on the on-set raid, the lab raid, and on LTO), only this is when the actual camera card may be formatted. For you, it would be just an extra ssd/sd or cfast card. Amazing anamorphic work, love the effort you put into this and just hoping that you won't get bored by making videos of whatever you tinker on. I'd even watch a second channel with more down to earth around the house projects, it's great to see into the thought processes of people like you. Thanks for being : )
Close your eyes, listen to this video, and tell me it isn't Kermit the frog explaining two-stroke pipe theory in a Norwegian accent. Great vid as always buddy
Try solar flux type B mixed with alcohol and apply on the inside of your parts
I agree. Find a Dynojet and give it a run. I forgot who the poster was but he was at 20HP with his 50.
It would be very interesting to see how a bigger stinger would act?
It seems like your transmission losses are around 2.5hp, as can be seen when the dyno spins down. Unless there’s some weird software stuff, it seems like the dyno should be able to measure the loss just as accurately as hp gain, the drum is just spinning down instead of spinning up. The more loss, the faster the drum slows down.
Good call - there is also hysteresis to consider, especially with that belt drive primary. If I understand the setup correctly, the clutch is disengaged when he finishes the run, so we're seeing the spin-down numbers of the transmission only without the belt primary, so his loss is probably even higher than 2.5hp. Probably a safe bet that he's at least 15hp at the crank right now.
He should quit screwing around and obtain a dedicated 2-stroke engine dynamometer! How obvious can it be? @@MikeyAntonakakis
Someone probably mentioned this but to weld stainless pipe together you must purge the inside of oxygen via argon, this with a ton of practice will make the welds look better. You do need a duel regulator.
Love the dyno testing from my experience if you have leaks at flange to cyl will run much worse interesting trying different stinger sizes also pipe length would be good is it possible to have the centre cone to slide an inch or 2 by sleeving it then having a big clamp to keep fixed kind of like a car exhaust fits together you could change overall length a few inches simply for dyno runs
You are a genius, appreciate the knowledge that you share with us
Is the spark strong enough for those rpm’s? That’s a lot of timing advance. I hope you decide to start reading comments again even to consider what folks are saying and question it. I wish you luck on your adventure in any case
I would suggest that you consider going to a larger carburetor such as a 28 millimeter macuni the larger venturi volume will provide superior cylinder filling resist stand off and is not effected by pulses also you use smallet jets and compinsate avoiding the knife edge ovet inriching of the smaller carburetor
I would think about what your egt temps are so low, power seems to be increasing with pipe temperatures maybe poor atomization of mixture, or lots of exhaust gases staying in the combustion cylinder timing doesn’t seem like it has much affect on egt so I’m leaning towards a port velocity problem, the engine seems like it has plenty of flow but doesn’t seem to be building cylinder pressure like it should you possibly try heating the crank case to help atomize the fuel, the cylinder stuffer didn’t work which kind throws low transfer port velocity out the window, I think the exhaust port is probably working too well and pulling air fuel mixture out of the cylinder or secondary pressure waves canceling the initial wave out, making the transfer port less effective a little nitrous oxide would actually tell you quite a bit because the intake flow is less critical
you could try to play with those waves by wrapping the expansion chamber with insulation, giving more heat after all you can see a change with a cold pipe and a hot one, so what is a really hot one like?? , also moving the exhaust ducting a bit away from the pipe so you are not getting any negative pressures from it sucking out the gasses, two simple tests to eliminate possible issues.
Is there a reason why the stinger is only 1 inch long ? I've never seen a pipe that the stinger is open to the atmosphere so abruptly most are 6 inches or more. I'm not saying its wrong but its just nothing like I've ever seen
This stinger is not a stinger. Much to short!
More like a baffle than a stinger
In cars, they usually take
1 degree of timing out for each PSI of boost..
Sounds like it might be time to get yourself an air/fuel ratio sensor and gauge.
Would an outlet pipe tip extension make any change? Mabie more chamber gasses would be available for the power-band. Look at an 80's yz80 exhaust pipe. It has more chamber volume, and longer exit length
they also need room for a spark arrestor though, for mass production... standards, or whatever they call them.
You are amazing!! Building a chamber from scratch is bad asss! Did you get my comment in your last video comments section? Donut has you in their latest video about horsepower! So cool
Because this is the internet someone is going to say "by the sound of you slapping the pipe your pipe is wrong in (palce x) by about (really precise number)".
I would that the stinger length is important the longer the stinger provides the tuneing also try wood peaces or packing your pipe with sand the wood you can burn out and the sand if packed well will allow you to make intricate bends no collapsing and good smooth flow as you can have now welding beeds inpedeing your pipe in the inside diameter no hot spots you are brillant but I learned this as privateer against factory backed competition
I think you should start coneing your stinger and using a smaller hole and then going larger cutting it off as it goes up🎉
IDK too much about 2 strokes but I remember when I was young with putting new piston and rings in late 80's kawasaki and having to drill a hole in the piston in a specific place.
This is done during engine preparation, the piston is drilled at the level of the exhaust bar in order to improve lubrication at this precise location
you should look into hydro forming a pipe , a pressure washer and some thought out pieces, smooth pipe
Did you design the pipe by simulating it in engmod? and if so did you remodel the engine as it is now?(with the lower exhaust floor, different angle transfers, rotaryvalve) or did you use an old unupdate model to design the pipe? cause i would think that things like angelarea and case volume would be important in pipedesign.
Hi Alex! Maybe my question is dumb but, what about squish gap and CR? Less gap, more turbulence, better mix burning, more exhaust gas temperature... Also less burning time, that means less spark advance... Maybe you are in a "too safe zone". I dont remember the last yime You checked that... Anyway, great job man! I always learn something new in your videos, and inspire me for keep my own project alive. Thanks.
First impressions regarding the new expansion chamber-the problem doesn't reside with resonant frequency or the movement of A/F mass! At least two individuals commented in the last video that the boost port should be blocked off. I think they have an excellent point. There's something wrong with any 2-stroke engine that has its torque peak at the same rpm as its peak bhp. For certain, this seems to be a porting problem. Until the bhp occurs at least couple of thousand rpm ahead of the peak torque, the engine will NEVER achieve the desired power performance. Right now, the PIP cylinder seems to be a dud...
Could very well be👍 Strange tho, as the port layout is pretty much "standard". Blocking the C-port wouldn't take much work, I'll try.
Could you put slip sections in your pipe in order to vary the reflection timing in the exhaust? Also, why is your header pipe so short? 👍👍
How about a sliding pipe like I e seen on go-carts before? Start long and shorten as the revs climb
I have to ask that in the old days we used to work on shaping the ports on our to strokes it was very efective
You should find out how to make a see trough pipe and use a slowmotion cam to see how the pulses move inside the expansion chamber.
Drive chain does look extremely lose for just running it on the dyno
Proud of you making pipes now bro.
Take the FARRRKN stuffers out!!! Show us your secondary intake now.
There exist programs, I believe for cellphones, which measure your vehicle acceleration, your displacement, and with input of vehicle mass (including rider), can calculate horsepower. Since you basically have a rideable bike, you might consider this method as a data for comparison to your inertia dyno and your bench dyno. Not suggesting this method for all your development, just as a reference value for validation.
It is already a big challenge to produce several equal dyno pulls in a controlled environment. Trying to produce multiple comparable pulls outdoors with all the external factors thrown in is as good as impossible, especially when the measured differences are as small as they are here. Those programs are nice for bragging rights if you own a muscle car but useless for developing purposes.
Wanna make a seamless expansion chamber? Shape and weld 2 flat pieces of sheet metal together around the edges leaving one small opening, then use a pressure washer to blow water into the opening and the pressure will expand the sheet making it into a pipe. Try it it works well Vw
Hydroforming
Kinda wonder what will happen if you make the inside of the stinger into a slight cone shape? like from 14mm to 16mm.
You can purge weld if you are using tig
You basically have a double outlet from the regulator to pipe on a bung and blank off the other end so you can fill the exhaust with gas while you weld it
This should stop the welds hanging through the inside
Since you have a table lathe, get a piece of hard wood longer than, and wider than your desired pipe, lathe the shape, use that as a buck for forming a pipe with fewer pieces.
you should try hydroforming a pipe. ive done it a couple times to make 2t pipes for my mopeds. works a treat
wonder if creating a cable driven slider on the primary tube to alter the length would be useful for tuning the pipe to the engine, or perhaps a variable annulus on the end of the pipe?
I honestly believe holding the exhaust Port size for their back using a larger combustion chamber but shorter and then a small stinger cone down to 10 mm minus
love your progress will keep up with you for years
Any thoughts toward "ok, i got the pipe and iggy peaking, but egt is low. Lean the carb to increase egt to more ideal levels"? Run all the variables you can control on any single mod, THEN mod further? My thought is more heat is less dense, so the inertial conflict of colliding waves will wander up the curve, possibly dragging your peak with it?
👍 Leaner carb is next up, in tandem with building a new pipe.
Came here to say this - clearly there's still something fundamentally wrong happening, reflected in the low EGT (some is sensor lag, though, takes some duration of heat to get the probe heated up, even if it's open tip probe, so it's likely reading lower than actual). Would also love to see the 16mm stinger with the curve!
maybe try various length pipes before the stinger and put the stinger in that, clip them in like they are a stinger, Do you think a 5 inch 125mm tail would help you get the revs and the power
Awesome 👍😎‼️ I love your Channel and always be happy that you not give up 👍👍👍‼️The only thing that i did not see is Tape, because the most Racer hold together with Tape. I don't know if it for POWER or to hold all together or Aerodynamic?!? Without Ducttape the World brakes in Parts.
Greatings to you/family stay safe, healthy and share love!
How about an adjustable telescopic center section to your pipe in order to change its effective length for experimenting.