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- เผยแพร่เมื่อ 26 พ.ย. 2024
- DIY head mod that IMO is the best bang for your buck modification you can do to your YZ250 smoker. Will work on all modern YZ250s, 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Link to Part 2 of this video... • 1:11 YZ250 2 Stroke He...
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Thanks for watching!
upallnight91@hotmail.com
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When I used solder wire, I cut it just a tad smaller than the cylinder bore, (about .020" is good for this size engine, a place for the squished wire to go), left the wire straight, and put a piece of electrical tape in the center of it to hold it in place. We can do some things differently, but I can tell so far that you like to do good work. You give mankind hope man. :)
Thanks brother :)
I JUST SAVED YOU A LOT OF TIME :). After some lapping on the gasket surface of the head, you do not need to keep assembling it and check squish. First, measure from the gasket surface to the machined bolt head surfaces, (3 of them, opposing each other, and mark them), and write those numbers down. Do the subtraction of how much you want to remove, and just measure those same 3 points with your calipers as you lap the part. There is a small burr on the edges of those bolt head spot faces, so knock them off first for accurate measurements, and you only have to measure squish the first time. Maybe a second time when you are done if your are paranoid. :)
I found a dial indicator is better to use than solder wire. I used to use thinner wire for smaller engines I build, (.032" diameter flux core) and cut the squish for stroked cranks to .020" (30cc engines, and we go as close as .010"). I measured with the .32" wire @ .020 squish, I was getting about .002-.003" of error, (as you rotate past TDC, you can feel the wire never fully compresses.). So that was fine for always setting my squish at .020". But I found that if I wanted to go to .010", (for example), the amount of error was different, so I went to an indicator. The wire will have different error depending on how much you squish it, and we just measure the wire not considering any error at all.
I always wondered how much error was in the solder. Figured there had to be some for sure
I am going to do some head work for my 2019 YZ250 also. I picked up 2 other heads for development, one before and one after 2011. From my measurements, it looks like the lower compression head will be the same CR as the pre 2011 head if you remove .0085" from the gasket surface.
Yes. They are the same profiles once the 2011 and newer head is milled down to match the 5UP head.
@UpAllNight91 No need to find the middle ground, just tighten the squish all you can as long as it doesn't hit the head on the overrev, increase the comp as much as your fuel allows but make sure to get 15° ignition advance @ peak torque, and get a CDI that allows for a custom ignition curve, that way you can retard the ignition on the overrev and gain overrev even with a higher comp
Thanks for the tips. Them after market CDI's are not cheap. Otherwise I would surely be willing to see what I can get away with lol
The squish for best power is parallel to the head and piston, with a sharp 90 degree angle on the inner edge to the combustion chamber. Good rule of thumb is no less than 1% of stroke, so there is room for piston/rod/crank stretch at high rpm
Yes sir. You don't like adding a small amount of taper to the squish clearance?
@@UpAllNight91 not if i can help it, no. It also reduces the risk of detonation by having it parallel. Lots of testing of this where done at Aprilia RSA 125 motogp team. The one that produced the best power was a parallel squish, with sharp angle on the inner edge of the combustion chamber and a toroidal shape. They still have the record for making best power/cc ratio to this day without boost, 54hp at the crank. Their development stopped when Dorna banned 2 strokes from motogp. You can read and see pictures of all this at the kiwibiker forum, ESE's tuner thread. I've been interested in 2 strokes for most of my life and have searched far and wide for all info i can get, theres no other place like that thread. If u want to understand how to make a great 2 stroke, read it. Its over 2000k pages, read it all and u wont regret it.
@@Rustyy42007 was the 54hp RSA. So more like 15 years ago, not 30. Development started in the late 90s. Jan wasn’t even working for Aprilia in the 80s
@@Daniel_Martin152 yes you are right, my bad. Got the years mixed up, will correct that👍🏼
My wife once modified my head. Was a bit more then 2 strokes tho.
Did she take the time to polish it up at the end?
@@UpAllNight91 she actually stripped threads tourqing on his bottom end and then inserted a helicoil, which caused a fluid leak.
Ohh boy. How---------------- "progressive". They are always thinking with their genitals, and not their brain.
Your piston looks like it's seen some pre-ignition. Detonation looks different. The stripe in the middle of the dome running front-back is from pre-ign. Your bike was/is at the edge of your fuel octane level. You may be able to get rid of it from a cooler plug. Pre-ignition and detonation are two very different effects from two very different causes.
Incorrect. Detonation and Pre Ignition are exactly the same thing 🤦♂️ unless you have a ton of compression AND very retarded timing thatll let it burn long before TDC
@@Shadow0fd3ath24 No, look into it. Pre-ignition happens prior to the spark and detonation happens after the spark. They are two separate phenomena with very differing damage types. That's why there are two separate names - for two separate things.
@@Shadow0fd3ath24 Further, detonation is caused by the advancing pressure front(after the spark) and pre-ignition is caused by a hot-spot in the chamber(before the spark - hence the name).
Two very different things.
@@burtlandcastor8359 There has always been some grey area with those definitions for me, and "pre ignition" is clear that it happens before the spark. But to me, that is like dieseling, created by a hot spot or too much compression and hot burn temps, and even creating another front when the spark goes off. The bottom line to me is there are several things that cause a expanding/burning front, and it is only suppose to be the spark plug. I don't think going to a colder plug will help. The plug range is selected as a guide to jetting. The right range plug will give you the nice light brown color/plug condition with the right jetting at full throttle. If you change that plug range and use plug color to jet your carb, (any carbed 2-stroke), your jetting will be off. The colder plug releases it's own heat faster, (more hollow porcelain looking into it), and would look richer. You jet it to a light brown, and your going leaner than you realize, (for example). How fast the heat releases heat does not really have any effect on the combustion temperatures, just the plug color.
I had a twin air cooled snowmobile in 1974 (Suzuki Nomad), and it ran one cylinder plug with a good color, the the other cylinder would always foul a plug. It only had one carburetor, so I just put a hotter plug in the cold cylinder just so it would burn the deposits and not foul. That was my 10 year old fix. I am sure it could have run better. :)
@@EarthSurferUSA A central erosion of the piston is a clear indicator of pre-ignition from an overheated negative electrode. When the erosion is at the junction of the chamber and squish band, it is detonation. Too much squish thickness will cause carbon build-up at the periphery of the piston and squish band and can cause pre-ignition that will erode the piston at an edge, especially if lean.
The plug can tell you a good deal of what's happening in the engine but the piston shows a great deal more.
Two-strokes are ALL liquid-cooled, even the ones with no water jackets. The primary cooling liquid IS the fuel, the "cooling system" of said engine is the secondary heat removal.
I plan on doing some special head work, a design of mine to test. But for my YZ with pretty good top end power, but softer low and middle, (it's like a big 125, kind of), I think I am going to reduce the squish (also if not only) by lowering the cylinder and exhaust port for more mid range boost. I want more power down there for aggressive trail riding.
I also still have to jet it well, (sick rich stock), before I decide what to change.
I lifted my barrel and put 15cc head on mean midrange and revs to 11500rpm with a stock pipe hope that's special enough for you.
Is 11500 high enough for you? I'm getting around 13000 out of mine
@@UpAllNight91 mines a 250 not a 125 cheers
@@skyhawk409 ahh ok.
@@skyhawk409 I am not riding on the modern full throttle MX road race courses we have today, (because of the faster four strokes), so I personally am not interested in an engine that revs that high. 11 and 13 grand from a 250 2-stroke, that has to be going past mean piston speeds. A MX 250 2-stroke is just fine revving to 9 or 10 grand IMO, but a 125 should do more. If I tried to get that top rpm out of it, the low end and lower mid range would be weak, and I want power there.
High rpm is important for drag racing and today's road race MX tracks. You can have it. :)
Your videos are great. I just got a yz250 and I need some help taming this beast. I haven’t rode two strokes in over 15 years I’m just an old vet A rider that’s been riding 4 strokes. What would you recommend to do frist. My bike is stock minus spring changes to my weight/skill
Thanks. Congrats on the YZ250! For me the best thing I did that cured the bikes overly snappy hit and tip in was installing Vforce 4X reeds and using the stock reed spacer with the 4X reeds. It gave the bike 250f type throttle control down low and in the lower mid range yet gave it a 450 type pull up top. Kinda the best of both for me. I would suggest trying that before going in with flywheel weights and longer gearing. I actually did two videos on these reeds if your interested here are the links... th-cam.com/video/WleTE9GVRMk/w-d-xo.html and th-cam.com/video/V3DrzAaAcXs/w-d-xo.html
@@UpAllNight91 thanks again. I’ve watched pretty much all your videos. I was leaning towards doing the reed first, I live in Ontario Canada. Would there be any Jetting changes you think?
@@Nelsonmccallum27 the jetting should stay the same, with maybe only minor adjustment at the air screw if any. I eneded up turning my air screw in about a 8th turn and that did good
@@UpAllNight91 do you have the part number for the reeds Canada sucks for bike parts
@@Nelsonmccallum27 The part number is V4X07EM . You can order them right from here... mototassinari.com/finder-results/v4x07em.html
Notice he is squishing the solder at 2 ends opposing each other in the cylinder. There is another method where you just reach a piece through the spark plug hole, (which may work with two pieces opposing each other in the bore), and to one side of the bore and squish it. The one wire through the spark plug how will let the piston rock as much as there is wall clearance to rock, and your measurement will be bigger than it actually is. You won't know how much bigger.
What if you stuck two opposing pieces down through the spark plug hole :)
Well, I learned something. Lapping with sand paper on a surface table,---using adhesive spray. If it comes off easily and cleans up easily, that is a great idea. Which is your favorite spray?
Hmm not sure if I have a favorite . I just grab what they have and hope for the best lol. But I have noticed some are better at drying faster than others
Bout to do a second cylinder head found on ebay using this method. Im thinking a perfect woods setup= athena thinner base gasket (lowers ports), then set squish to match .04-.045. Then open (dome only )to 5up cc. Set ignition timing, fuel, jetting accordingly. Goal is to put into third and set it and forget it, more low end torque = less clutch, less shifting. Just changing gearing would give me more torque as well but less power spread.
This set up will lose some overrev but ok for the offroad i ride. Still enough in open sections to get to next turn.Whatcha think?
Athena "race" base gasket is 0.45mm the "oem" athena is 0.5mm where actual oem stock is 0.6mm. Cheap tusk brand btw is 0.7mm. Of course these measurements are taken before installing so doesn't count for compression. Just one more area of customization
Hello. I think it will work good but keep in mind the lower cylinder will also bump up compression, which will be good for what your looking to do. But you will want to keep track on pinging and make sure you're fuel is up to it. That should make a lot of torque though for sure.
Cc head with spark plug in is what I allways do. Put a hole in your flexy glass.
I've done it like that too and that works good. I only started going through the spark plug hole when I started doing some heads that the squish is so tight that it got harder to get the air bubbles out of the far corners.
@@UpAllNight91 I have a barrette graduated tube, glass with a glass valve. You put grease on the tapered glass valve, and just press it in there loosely. What a weird valve, like from the glass blowing days, but it works. The head is placed on a table upside down, and the barrette is held by a rod bolted to the warped table. A piece of plexi glass is greased on the head gasket surface, with a hole in it for the barrette glass nozzle.
A syringe is easier. :)
@@EarthSurferUSA would be interesting to see that! I will be doing a yz125 here shortly. Gotta run out for some more plexy glass for this job
Thank you! What volume you think is recommended for 87 octane fuel? That's what we have here. Than you
Your welcome. Honestly I can't really say as I don't have much experience trying to tune them in for octane that low. But if I was to try I think I would start with the current 5MW. I would CC the head to log its stock volume. Then I would shave the head down to get the squish clearance no tighter than 0.050" which is about 1.27mm. Next open the dome up to bring the overall CC's back to what it was before it was shaved. Test that out. If it seems to aggressive for 87 octane then you can go back in and open up the dome area even more until the compression is low enough for 87 octane. A little at a time until the sweet spot is found. It may actually be ok first try with 5WM stock overall volume and 0.050" squish, but if not just open the Dome up a little more
The 22ml is that because you use the plexiglass thats flatt and the piston is domed
When I do it im on 20.6ml but thats on the cylinder with the piston not the plexiglass
Yes sir! You got it!
Am I able to do this to a 2004 ktm 125SX ?
I believe so. Some of the KTM have inserts in the head and cant be done like this. But ones without the insert should be ok.
How does a tighter squish effect the crank or other mechanical parts? I don't think it does, that is easily measured. But what a squish that is too tight can do is increase the squish velocity, (per old TSR software I have.), that can lead to detonation. Now the detonation can be hard of the mechanical parts, (some pretty nasty spikes of energy), but it also should be eating aluminum parts.
Yup. I have found it can wear cranks faster when tuned to the max, but I think its mainly due to just because its making much more power over all
@@UpAllNight91 "Tuned to the max" and running on gas is really good just to get another 5 hp out of a 250cc bike. The crank parts should have no problem with that, unless manufacturing is actually the problem, (which won't last as long in a stock motor either.). If my radically twisted 2014 Yamaha OEM front fenders are very poor quality, (and Yamaha stiffed the dealership with them. I had to go after market and out in my own mounting holes,--because I can't stand the stupid art plastic today.), I could assume other parts we buy from them can be also. The global competition with communism is not a friend of quality expensive procedures.
@@EarthSurferUSA yes sir!
i asked what elev you ride i watched your other vid and you did say sea level florida
Stick figure in the background 👍
You know it! LoL
Just to verify, that’s an M14x.075 threaded hole for the spark plug. The air fitting is different but does thread in about 1/2 way and then starts to bind. Is there a chance to damage the threads using the air fitting? I’m about ready to give this a go. 👍
Hello. You are correct. It binds but nicely and I have yet to harm any threads and cause any damage. Just lightly seat it down and it works great with no damage. Let me know how your head comes out!
Will do! I actually gutted a spark plug and had a hex socket that pressed down into it. This should be a fun project, I’m just not looking forward to sore thumbs.
@@spoderacing3910 LoL. Sore thumbs for sure. The 125 goes so quick and hardly much work but the 250 is surely a decent job. Good job on the spark plug attachment. Might put one together myself. Can surely help keep eye on raising the domes roof
@@UpAllNight91 I got it done! Squish at .045 and opened the dome to 21cc. I got lazy and stopped at 21cc. But the bike pulls harder everywhere and has a bit more of a midrange hit. I think with some gearing changes I can pull a gear higher through the corners. It also cleaned up my jetting. I’m running 100LL with mine.
@@spoderacing3910 oh man thats bad ass! Yeah its tough opening that dome bacl up lol. Did you also have to go leaner on the main? Yesterday I was able to break in and test my fully rebuilt motor. With the exhaust polished, v force reeds added and that air box mod added man she feels like she gained a few good horses. But I'm still gonna revisit the head and do another head and see if I can come up with even a better profile.
I give u a like and sub to only cause of this hack. Build port chainsaws not dirt bikes no more. Them days was a blast tho
🤣right on and Thanks!
Man,---you need a machine shop. Check out a company named "Tormach" for some pretty affordable, light duty, (good for this stuff), CNC mills and lathes.
I have been living off their 12 grand 1100 mill and a 3 grand manual lathe since 2007 porting small 2-stroke cylinders.
You need to build a shop.
Man your so right. I need more space too. We bought some land and looking to build on it and move there within a few years. I've totally out grown where I'm at now. And yeah I definitely need some machines to knock this stuff out.
@@UpAllNight91 I have a ton of machine experience and could help you out if needed. But I can tell, as you learn, you do pretty good work. Myself, I get a lot of gratification when my parts come out perfect, and so do my customers. :)
@@EarthSurferUSA nice. What are you machining for your customers?
Sir, Ive done same thing but it becomes so hard to Kickstart ,, i damage kickstart 2 levers already and a pair of shoes,,, how to get away with this issue?,,,,
You have the compression too high. You need to open up the dome more.
Just picked up a 24 YZ250 been off a bike for 14 years. You think swapping to a 5UP head is worth it? I have c12 in the garage I’ll run it straight if I have to. Thanks Chris!
Hello. Congrats on the new bike. If you think your going to do any motor mods at all I would start with the head as thats the biggest bang for the buck. The 5UP head is the best stock head for the YZ250 and surely feels like a solid upgrade over your 24's stock head. The 5UP head wont be as good as a good custom head but will be right there with some of the aftermarket heads like Apex.
@@UpAllNight91 I was also looking into apex but seems like they still have stock compression. The 5UP looks like I’ll get tighter squish and a small boost in compression just by bolting it on in stock form and I shouldn’t have to trim the dowels. I have straight c12 in the bike which I know is overkill but I’ve burned sleds down from bad fuel so it doesn’t bother me to spend the money to know what I get. Only plans are a factory fatty and shorty silencer and ride her!
@@Aad2797 Yup, some of the apex heads even have slightly lower compression than stock. They are set to be pump gas friendly in most cases. The 5UP head is no really pump fuel friendly, needing at least 50/50 to run safely but it is surely a good performer.
@@UpAllNight91 scored a new 5UP on marketplace for $100. I’ll do the swap once I get some actual seat time on my bike. Dealer put c12 at 15:1 for break in said run her for an entire tank full at that ratio then go to 32:1.
@@Aad2797 Ahh good find at a good price! Nice of the dealer to use C-12! When you bolt the 5UP head it will instantly sharpen up the throttle response and will sound like a race bike.
I have a question
If I see a small amount of Grey discharge from my exhaust valve vent tube, do I need to resurface my head?
Thanks
If its coming from your exhast valve vent its most likely just 2 cycle oil that collects in the power valve area being discharged. Its normal on these bikes. You should be ok
More compression will take away from top end power
Thats correct
What about the 2000 head
Would a 2022 head running 99 octane fuel In the uk, be ok cutting squish to 0.040 and back to stock compression?
Hello. Here in America our octane is rated different. From what I understand our 93 octane would perform as if it was higher octane than a 93 octane in other parts of the world. We use motor octane rating plus research octane rating method. So its hard for me to suggest what octane rating would be ok with what head profile in your part of the world but I can give some pointers. If its unleaded fuel (not race fuel or a mixture of race fuel with pump) meaning there is no lead in the fuel at all then you will not want to set the squish any tighter than 0.050". As for the overall compression ratio, i would attempt to start with the same compression ratio as the stock 5WM head. I think at 0.050" and near stock compression she will run great on just about any premium unleaded pump fuel
Do you happen to know the difference between the YZ250 and YZ250x pipes? I suspect the 250x pipe is tuned for more mid range power, but that is just a suspicion.
I honestly dont know the difference. Do the have a different part number?
same pipes, only the x model have low compression ratio ...
@@lametraserillos1 thought they might be the same pipe. Didn't know about the head though
@@UpAllNight91 I think I could tell by the stamping that they are actually different pipes, (don't know part numbers. But if the same, then same pipe. I will be wiling to bet the YZ250X pipe is tuned for a lower rpm target, and slightly longer basically. If you compare pictures on the bikes side by side, I think, (if I remember correctly), you can see a difference. I know the engine could use more lower rpm for trails, (the stock YZ250 is tuned pretty high, like it has to keep up with a 4-stroke on a 60mph track.), so if Yamaha cared, they put a lower RPM tuned pipe on it for trains. I am going to run my YZ250 in the trails, and maybe want to try the YZ250x pipe.
@@EarthSurferUSA yeah could be longer. In the past I have used pipe spacers, it was like a 3mm shim ring that went into the exhaust port before the pipe. Was easy to make out of aluminum and surely increased snap and bottom end. Maybe worth a try for you?
Is there a rule of thumb for overall cc's vs combustion chamber cc's? If your shooting for 22cc's on a 250 would that mean you'd want about 12cc's on a 125?
I'm not sure if there is a rule of thumb on CC. I know there are people that know or understand the math on this but I never applied myself to learn that. Plus I think every motor is different too as there are other things that play a factor like exhaust port height and piston crown profile
I think so, because a compression ratio is measured in volume, for example, 13:1, which means the cylinder sweep plus the head volume is 13 times bigger than the head volume alone. CC's are the unit used in measurement to figure out CR. But on a 2-stroke there exists it's own measurement of cylinder volume that is only measured above the exhaust port, instead of using the entire 125cc or 250cc full stroke sweep, (like a 4-stroke uses). I see many people measuring CR with a 2-stroke using the full stroke 4-stroke method, (with working results), but IMO, it is best to compare CR at the top of the exhaust port for 2-strokes. That means your cylinder volume will change depending on the open duration (height) of the exhaust port from engine to engine.
Yer iwe seen i videos from the us that premium pump gas i like 89oktane is that right
I meen poor gas here in Danmark is 95 and premium i 99 and vpower we have also on every shell station
But shurly it cant be right that premium is 89
Here in the states they use the ron+mon method of labeling a fuels over all octane. But in other countries they often use only Ron or only mon so ita hard to compare between what we have here and what you might have there
I have a 2001 YZ 250 as well I’m looking to get the head mod done. Do you recommend staying with the 01 head or try and find a 06 head? Thanks
Hello. It really doesn't matter which one you start with, you can make both come out identical when they are finished. If I remember correctly the 2001 head is the same as the 2011 and later head here in the states. I have done that head and the 5UP 2006 head and they both come out to the same spec. The only difference is with the 2001 head you will have to mill or shave the matting surface down more to get the squish band where you need it but thats the only difference and the end result is the same with same spec potential
Are you doing this mod for customers as well, Im interested in getting it done.
@@carlosjvelazquez7673 hello. I do but its more of a courtesy. Since I don't have the machines to do the job quick and easy, I do it like seen in the video. But they do come out well and honestly for my own bike I wouldn't have it any other way. Where are you located?
Orlando,FL
I,m looking to by a used like new condition 2018 YZ X head 5mw for a good price. This head will work to do the mod as well?
N how much clearance would I get the squish band too ?
Depends on what your looking for and how much octane you plan to use. 0.050" is good for 93 pump, any tighter and higher octane will be needed. I set my YZ250 to 0.040"
Would this take forever to sand by hand?
Years ago I did on by hand. Took FOREVER!
@@UpAllNight91 lol. Noted, thanks for the reply
@@barkeep25 yes sir. But a cheap cordless drill will get it done no problem
@@UpAllNight91 did this to my 17. Stoped at about 0.045 of squish. Head cc'd as well. Man she is running amazing!! Only thing I've noticed is that I had to bump up 2 sizes on the pilot jet. I'm now running a 50 pilot 1/2 turn out. I was under the impression you had to reduce pilot after this mod? I've already checked for air leak. Lost no psi after about 20 minutes. Running 50/50 c12/93. Checked throttle, tried different needles, advanced and retarded timing to see if different. It wasn't. Float was checked and rechecked even lowered a little (richer) to see if different, it wasn't. Could it just be it likes a 50 or 52 pilot and call it a day. I ride at about 900ft. 70° rn. Thanks again
@@barkeep25 ahh totally man. I run a 50 and a 52 depending on weather. And I run 3/4ths a turn to 1 full turn on the air screw. Its mainly just the main just that usually needs to be leaner. But the pilot and fuel screw can often enjoy richer to keep pinging under control. Sounds like you got it and have good jetting skills. Sounds right on. What main did you settle with?
Will that inner dome come out I need to change mine I have new outer dome mine is leaking by the spark Plug has a little crack
Stock head or aftermarket like the Apex?
@@UpAllNight91 My stockhead. I sended it down.I think I fixed it I'm getting my apex head today or tomorrow And my new reeds .
I wanna let you know.My bikes broke changed the crankshaft.Seal the water pump seal and it's still bogging down so I took it to shop yesterday I'm have them fix that an put my new carb on apex head an re Jett it I gave up on bike
@@michaelgarland579Oh ok. Hopefully they get it done fast for ya
@@michaelgarland579 ok
*1,7018mm clearance
That rooster
LoL yeah!
Bro I was in class watching this in my air pods and I was like who the hell keeps playing a rooster sound and then I finished watching it after class and was like it was in the video😂😭😂
measure the head before you cut it
Ohm your coil at 5k form me
Need a reference with my coils at
So, why can't you just change the head? :O
You can. There are options out there like Apex. But I like to do my own so I can dial it in right where I want it
@@UpAllNight91 did bad gas make my piston fail? I have the 05 head
@@RideWithTheWolf surely possible. The yz250 doesn't like poor gas at all. At least 93 octane fresh and even then the 2005 head will be a little high on compression for pump fuel. If you are hard set on pump fuel then your gonna wanna order the 2011 to current 5MW head . It has much lower compression and works decent with fresh 93 pump
@@UpAllNight91 I haven’t even seen 93. 91 is highest out here. Would an apex head help?
@@RideWithTheWolf yes the apex head would surely help with pump fuel. Mainly the MX apex. It is very pump fuel friendly
0,5mm é muito apertado bate pino
You can shorten the pin. Thats what I do.
Find a friend/shop with a lathe so you can really get it 100%. There are good programs from Mike Forrest that will get you a real nice head setup.
Who is Mike Forrest?
A machine shop can mill that head for $50 to any chamber size you want. Same as porting the jug. A few people want to believe there’s some special “VooDoo” when modding and porting two stroke engines. It’s a joke. Or it’s called quench, not squash.
Hello from my understanding quench is more of a 4 stroke terminology where its not all the way around and squish is more of a 2 stroke terminology where it goes all the way around the combustion chamber. The term squish has been used in the 2 cycle world since before I was born by even the greatest tuners and its how most know it. I agree a machine shop can knock out the milling quick and easy. However I do like to make sure its dead set to the clearance I'm looking for and it might take a few trips to a machine shop to get it that dead on as long as we don't over cut it. This video is really for the home gamer tinkerer that wants to tackle it on thier own. Heads can be sent out to Pro circuit or HP and cut for like 150 bucks and its plug and play. For me I like to dial them in and will try and few different profiles, narrowing in on the perfect profile that suits me and this has served me well.
You talk too much