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- Опубліковано 19 чер 2024
- In this part I will polish the exhaust port, re-chamber the head, and start her up!
Links to videos on Head mod...
Part 1 • 1:11 YZ250 2 Stroke He...
Part 2 • 1:11 YZ250 2 Stroke He...
Links to doing the top end...
Part 1 • 1:11 My YZ250 top end ...
Part 2 • 1:11 My YZ250 top end ...
Part 3 • 1:11 My YZ250 top end ...
Links to Vforce 4X review...
Part 1 • 1:11 VFORCE4X Test rid...
Part 2 • 1:11 Follow Up VFORCE4...
Donate Race Fuel link... www.paypal.com...
Thanks for watching!
upallnight91@hotmail.com
Wish I had a mechanic like you that took pride in their work. That lived near me lol
Yes I hear you.. around here people want to charge top dollar it's insane. That's why I learned to do it myself. I love repairs! It makes a guy feel proud
I love this guy, good people
I like the way you leave your mistakes in the videos, since those are what happens in real life. So many people try to edit out their mistakes, but the mistakes help us learn more.
For sure lol. I try to keep it as real as possible because mistakes will happen.I also feel it helps the viewer not become discouraged, knowing its just something that happens.
Sooner or later he'll get burned by not checking ring end gap, that'll be a great mistake to make a video about
Thanks for all the great information!!! Another great video!!!
Thanks Joel!
It sounds much more crisp with the modified head with a tighter squish band clearance. Much better burning efficiency in the combustion chamber. I also do this mod to all of my two strokes as that squish band clearance is too big almost always. I grind/smooth also that edge off from the beginning of the exhaust pipe as almost always there is some improvement to be done. I don’t have Pro Circuit but FMF Fatty and Bill’s Pipes for example.
In one of my older 1992 KX 125 I found out that one of the side exhaust ports was open when it should be closed and it closed when it should be opened. It was put back together wrong. I just fixed that and now it works as it should. For example if you only follow the instructions how to set those KX 125 exhaust valves and don’t check it out with your eyes it goes wrong. Not by much but then those side exhaust ports does not fully close and open to wrong angle vs. the side exhaust ports openings.
Right on. Yeah almost every bike out there with a stock head has too much squish clearance for sure. And for sure the powervalves gotta be right or they just wont run right. I dont know how many I have found not put back in right and the bike ran poorly lol
Nice work! Like the rooster :-)
Thanks!
As always 🏜👍
Thanks Bradley!
should be checking your ring gap in the cylinder before assembly to ensure its not to small and check out the inlet and reed bolt backed out at 15.06
Hello. Yes. Further in the video you will notice I noticed the reed bolt. Good eye though. The ring end gap, I did a video on why thats not necessary on oem nickel plated cylinders these days if you are interested in catching
Here is a link to that video... ua-cam.com/video/5wdMNpgAAYo/v-deo.htmlsi=7ICCIKpDIuSUnxg1
Fucking sick timing man I have my cylinder off right now doing some polishing hopefully I can pick up a few tips here
Right on, I didnt do anything major. Just come polishing on the exhaust port. Its worth doing though.
@@UpAllNight91 yea I ended up polishing my transfer ports just for the hell of it there was some crappy casting crud in them, I would like to eventually port match them to my cases but I’ll have to wait until my crank goes to do that cuz I’m not tearing apart just for that lol.
@@Yz4Life Right, surely gotta split the cases to get that right.
Good info u should do video on what bolts to tighten after a few rides my swing arm bolt was loose an one of my motor mounts too now bike is good I love my yz125 2003
Yes, I have had a few request for videos about hardware, thread locker and such. I do plan to put one together covering all that very soon.
I gotta try setting the squish on my ‘05 yz125. I stay on top of top end rebuilds for it. Would be interesting to compare the difference. Not sure if I’d get another stock head to have cut or just get an Apex/aftermarket head that’s already shaped for it.
The head is the best bang for the buck for sure. Does more than any pipe or porting could ever do. For me if I can only have one mod and only one it would be the head.
And my bike does always run more cleaned out after a hard moto seams a little leaner and I’m running a 10 plug
Yeah its normal to run cleaner after cleaning it out. The hot plug thing is a slightly different feeling that clean vs needing to be cleaned out.
I’ll be interesting to see if you have to make changes to your head design and jetting on the newer yz due to the influences of the new airbox flow/design.
Also I’m keen to see what you think/feel about putting your heavier springs in the updated suspension. The valving is quite different (stiffer) front and back to the older models, while also incorporating the leaf style mid valve in forks.
I’ve got the shim valving specification sheets for new and old.
I’ve got a 23 yz250 and put in heavier springs for my 200lbs weight (4.8N front and 5.6N rear) but I’ve been struggling with tuning via clickers to get the compliancy. Feels like the springs aren’t controlled enough but going stiffer on clickers didn’t help, confusingly going softer did a bit in situations but really feels like it needs more overall control of the spring (probably the high speed). I’m guessing I probably need clamp shims changed to stiffen up overall but also maybe less in the face shims to get the initial movement.
Fun and games, I love it!
Hello. I can tell you I already made a jetting change and havent even riden it yet lol. The 52 pilot I put in ended up being too rich. Which is stange because it works great on the 2018. I checked and yamah changed the part number on the carb but I cant find what might be different or why the part number has changed since 2018. As soon as I went back to a 50 pilot it ran and sounded like my 2018 with the 52 pilot in it. The reason I am installing slightly stiffer springs is because I have a friend who owns a 2022 and his felt good and firm when new but after fully broken in and at about 50 hours it started to feel like it needed stiffer springs for me. I rode it back to back with my 2018 which currently uses 0.48kg up front and 5.5kg out back and his 2022 was surely too soft after nice and broken in. I do expect the 2022 to feel overly stiff at first but I'm hoping after it breaks in good it will settle to around where my 2018 is currently. I'm hoping not to have to dig into the valving like you are currently doing but if I have too I will. I noticed they changed the forks dampener assembly from 2022 to 2023, do you know what they changed with it?
@@UpAllNight91 with all stock I’ve currently gone to a 48pilot. That’s interesting with the carb part number change, I’ll look into it when I get a chance.
The forks are now the same as the yzfs. Longer springs (higher spring perch setting). I believe the damper assembly is also slightly larger for larger base valve piston which is kind of pointless as already too large and causes oil to piss through when shims finally open (there are heaps of shims on the base valve because of this and causes lag). Damping is obviously velocity sensitive and could do with a lot more.
It looks like you ride a lot of sand and hence you will need stiffer settings than many.
@@ChookChasersMX Yeah about 75% of what i ride is softer stuff. There are a few harder packed tracks around but its florida so most are softer dirt or sand.
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😅👍
Never seen anyone touch an exhaust port. Even on a 4t... power is made from the intake. That is a good idea clipping the carb spring though.
These are 2 stroke, the pipe is what makes the power band we feel. The exhaust is very important on a 2 stroke
@@UpAllNight91 I get that, but your intake and port timing is where you'll see the most gains. I'm not knocking what your doing, but I wouldn't expect to feel any results from polishing the exhaust port. Think of how much build up you get inside your pipe.
@@panic-revv85 I'm not looking to alter the power curve any so I didnt plan to change any of the port heights. I'm just looking to improve on its current curve. The exhaust polishing isnt a game changer by any means but it does help for sure, more so on 125's but surely helps on the 250 as well. The roughness in that port and the coolant cooling around that port causes a collection carbon and goo. After polishing it stays as smooth as the day it was done even many hours later. The pipe can get dirty but they get cleaned out from time to time and even replaced lol. Its surely not a huge HP gain but like any 2 stroke these little things add up to a package.
@@UpAllNight91I understand that. I generally like to clean up the base gasket where it protrudes past the crank and the cylinder ports. I been looking for one of those older yz heads. We've had a few 250x's and the squish is enormous.
@@panic-revv85 yeah I remember back in 2006 the YZ250's OEM cylinder base gasket protruded into the intakes path pretty well and I use to have to clip away the gasket. I dont know when but it seems they have corrected that since then, which is nice. Oh yeah, the 250X had have a very fat squish band. You can actually just mill that head down to a squish of about 0.064" to 0.68" and it will be exactly like the 5UP head. I dont think they ever changed the dome size or the squish width on any of the 99 to current heads, seems they only form them with more material at the mating surface to bring the squish further away and lower the over all compression.
Why don’t you invest in a small lathe? :)
God yes I need too. But I hardly have any more room back here. I do plan to when we move to our new place though. I will have much more room there.
Does tighter squish band need richer or leaner jetting?
In my experience you can lean out the jetting as the combustion chamber fuel mixture burns so much more efficiently with tighter squish. If you have larger squish band clearance you basically lose some gasoline from your fuel mixture as it is not burning it all that effectively. That’s probably also one of the reasons why manufacturers jet the stock bikes so rich.
I agree with Janne P. It does allow leaner jetting when the squish is tighter for the reasons he said.
So I’m about 5,11 I’m 15 and I’m coming off a 110 and never rode a 2 stroke. I’m thinking about getting a Yz 85 large wheel. What do you think because I don’t want to hurt myself trying to get a Yz 125 what 2 stroke do you think I should get?
I think a 5,11 the 125 will be better and safer. Them little 85's can get squirmy and loose on use adults because the wheels are too small and dont provide enough gyros for the stability we need at our size. Totally say get the 125 lol. You wont regret it!
@@UpAllNight91 ok I’ll believe you! I hope I don’t get hurt from the power and I’ll take my time and take it easy too!
@@korfrm1k the 125 and the 85 will feel the same, power wise. Even though the 125 makes more HP, its also heavier so they are about the same feeling power wise
@@UpAllNight91 ok good to know I’m also coming off an 110 so how long do you think it’ll take me to adjust?
@@korfrm1k Eeveryone is different but put in your seat time and it wont take long
Any wear under the ports doesn’t do anything to performance
That's correct. But thats the area I seem to wear out to the point the nickel starts peeling. So I'm trying to see if a single ring might extent the life of the cylinder in that area.
Love your channel, rebuild my 2019 crf 450rx snowbike using you video! I have a 2014 crf 150f won't idle and bogs out on the high speed! If I shut the petcock valve after a 30 seconds it runs good but won't idle. New carb last year and cleaned it still won't run right. Is it a jetting isue or ? Thanks for any imformation been working on it all day! The bike is like new not very many miles on it so don't think it's an engine issue.
Hello. When you cleaned it did you clean the pilot jet out well? And if it runs good after the fuel was shut off I would check the float, float height, and make sure the float needle is sealing good. Make sure it none of the jets havent come loose, that kinda stuff.
Wish I had a mechanic like you that took pride in their work. That lived near me lol