How To Rebuild the Top End on a Yamaha YZ125 & YZ125X

Тәжірибелік нұсқаулар және стиль

Rebuilding the top end on your 2-stroke YZ125 may seem like a daunting task but with the right tools and know-how, the job can be done quickly and save you a lot of money over going to a shop. In this video, we show the process of how to properly rebuild the top end on the legendary Yamaha YZ125 2-stroke. This machine is a 2019 model but the steps shown here will work for all newer YZ125 and YZ125X models, from 2005 all the way through 2020.
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Пікірлер: 79

  • @Bgatz1029
    @Bgatz10293 жыл бұрын

    He has his hand torques really dialed in. Love it

  • @andrewtrombley1333

    @andrewtrombley1333

    3 жыл бұрын

    bout 0.15 ugga duggas there

  • @aidanvelthuis1267

    @aidanvelthuis1267

    3 жыл бұрын

    Honestly 2.9 ftlbs is nothing. I’m not breaking a torque wrench out for that😂

  • @mozer30

    @mozer30

    2 жыл бұрын

    If You listen closely you can her his wrist click when the correct torque value is reached.

  • @herbalchicken
    @herbalchicken3 жыл бұрын

    I don't even own a 2 stroke, but I need to see this.

  • @mrmotocross6819

    @mrmotocross6819

    3 жыл бұрын

    What you also need is a 2 stroke. I grew up riding 2 strokes. I own a kx450 and a cr250r and the kx is my lazy day bike. The cr250 if alot funner to ride and takes more technique.

  • @joedirt9830
    @joedirt98302 жыл бұрын

    Thanks for the video. I could not do a top end with out it. Keep up the good work.

  • @romanatlol
    @romanatlol3 жыл бұрын

    Love that I’m watching this even though I don’t have a yz love watching it though

  • @hphillips7425
    @hphillips74253 жыл бұрын

    Good video. I have never done a top end but as good as the video is I would tackle this job.

  • @jobmxjojo
    @jobmxjojo2 жыл бұрын

    This is gold!

  • @tbgtbg6311
    @tbgtbg63112 жыл бұрын

    Makes me miss the 80's

  • @mattandkatchristie2552
    @mattandkatchristie25523 жыл бұрын

    The power valve cleaning is like open heart surgery jeez doc good job

  • @AlexxMarssh
    @AlexxMarssh3 жыл бұрын

    hilarious i bought top end kit from you guys and did this yesterday great stuff

  • @bird4dbk420

    @bird4dbk420

    3 жыл бұрын

    Same here! 😂

  • @elongenjones7270
    @elongenjones72703 жыл бұрын

    Wow. Awesome how to video. I want to see more.

  • @vince5946
    @vince59463 жыл бұрын

    Another great vid! you're inspiring me to do another build:)

  • @atuhumuzakenneth8129
    @atuhumuzakenneth81292 жыл бұрын

    So clean video, love 😍 it

  • @kensmith9334
    @kensmith93343 жыл бұрын

    Great video!! :)

  • @KimChoonSam
    @KimChoonSam11 ай бұрын

    Watched the video very well. If you see signs of coolant flow, check the level as you saw in the video. I stand on a stainless steel ruler and shine a cell phone flash on the back. It's normal if you can't see the light.

  • @javinlarsen6760
    @javinlarsen67602 ай бұрын

    Old video but only thing I noticed is when you went to file the rings you filed towards the outside, supposed to file toward the inside of the ring so it doesn’t create a sharp edge going against the cylinder wall.

  • @rmatvmc

    @rmatvmc

    2 ай бұрын

    Good point! I wasn't really trying to take material since we were in spec, and just trying to get the general point across. Regardless of direction I always clean up the ends when done. But yes, normally I would try to file in the other direction. We'll specify that in future videos. Thanks! -Charles

  • @ronk6073
    @ronk60732 жыл бұрын

    Why on earth would you hone a nickel plated cylinder anyway? The plating is designed to resist wear from the piston and ring, what would be the benefit of purposely wearing the plating? Nothing under that plating but aluminum... Good luck if you wear down to that!

  • @jeffgoetz7919
    @jeffgoetz7919 Жыл бұрын

    Charles is the best

  • @panic-revv85
    @panic-revv852 жыл бұрын

    I've always heard not to use a dingle ball hone on a 2t as it will chamfer the ports?

  • @gtmnicko
    @gtmnicko3 жыл бұрын

    With the 2001 yz125 power valve linkage does it have a retaining plate on top or just the linkage and screw going in to it ?

  • @mixtips637
    @mixtips6372 жыл бұрын

    I can't wait to get a 2 stroke to rebuild getting tired of 4

  • @dhananjayabandara96
    @dhananjayabandara963 жыл бұрын

    👍 good job thankyou ❤👍😊🇱🇰🇱🇰🇱🇰🇱🇰🇱🇰🇱🇰🇱🇰🇱🇰🇱🇰🇱🇰🇱🇰

  • @takeiteasy9019
    @takeiteasy90193 жыл бұрын

    Would love to see a complete guide on a yzf450/wrf450 as u have done with the yz's

  • @takeiteasy9019

    @takeiteasy9019

    3 жыл бұрын

    I do see u have a rebuild video on them 7 years ago but would really love a updated version on the new 2021

  • @bikerdude6119
    @bikerdude61192 жыл бұрын

    Just bought a bunch of stuff to rebuild my 2019. Man i love shopping at rmatv!

  • @rmatvmc

    @rmatvmc

    2 жыл бұрын

    Heck yeah! We love it too! How many hours on your current top end? - Wes

  • @bikerdude6119

    @bikerdude6119

    2 жыл бұрын

    @@rmatvmc 42 hours lol once im in there ,im going to look for signs of wear and take note of what is next

  • @daryleduardo7055
    @daryleduardo7055 Жыл бұрын

    What about power valve adjustment? Or are they not adjustable?

  • @mickelrosado84
    @mickelrosado84 Жыл бұрын

    Where can I get that wrench you used for the inside cylinder nut for torque spec

  • @BigElly12
    @BigElly123 жыл бұрын

    This looks way easier than I thought it would be lol

  • @juliandanielframe4311
    @juliandanielframe43113 жыл бұрын

    i ride a 1993 kx125 could this help a little?

  • @JAMES.111
    @JAMES.1112 жыл бұрын

    WOW

  • @humbertoexotic8673
    @humbertoexotic86733 жыл бұрын

    Y’all should make more warrior 350 vids

  • @trentonrobinson2745
    @trentonrobinson27452 жыл бұрын

    Did you drill those holes on that piston for the exhuast bridge or did it come that way

  • @awesomecooly123

    @awesomecooly123

    Жыл бұрын

    Some come pre drilled others don't

  • @ianheimaster7390
    @ianheimaster73903 жыл бұрын

    Can you do an rm85 next

  • @bryce099

    @bryce099

    3 жыл бұрын

    Literally the same thing

  • @mylescheney5583
    @mylescheney5583 Жыл бұрын

    I am currently changing my piston lest time I rode I though my bike was lacking power as I was out ran by a 125 and realised one of the pins on my power valves was missing 😂😭

  • @DADSGETNDOWN
    @DADSGETNDOWN3 жыл бұрын

    Heat Cycle Break in, then go ride normal? I always heard heat/Cool Down cycle, ride for 20 or 30 minutes without going passed about half throttle and without quick revs etc, then put about 3 or 4 hours on it before you really open it up. Ofcourse not only is that what I was told by a few shops but that is for much older bikes too.

  • @mattharrell4

    @mattharrell4

    3 жыл бұрын

    Yeah I feel like everyone has a different take on this. I’ve done a few top/bottom rebuilds and just ride it normally for the first ride. I’ll do a nice slow warm up and then try to give it about 3/4 throttle to help put some pressure on the rings and help seat them. I’d would bet that as long as you don’t run the piss out of it you’ll be fine.

  • @boostedpleasure

    @boostedpleasure

    3 жыл бұрын

    I bought a 21 yz250x heat cycled then did a 15 minute low to mid rpm break in ride. After that it was straight to the race track. As of today it has 16 hours all race time. No issues.

  • @DADSGETNDOWN

    @DADSGETNDOWN

    3 жыл бұрын

    @@boostedpleasure I ride my little CR80 for 3 years on trails, hills etc Hallin butt everywhere, not one issue, but did top end anyway.

  • @Redheadrider449
    @Redheadrider4492 жыл бұрын

    I have a 2002 yz125 and after I do a rebuild do I have to change the oil gas ratio for the break in period. Thanks very much

  • @austinhoffa99
    @austinhoffa992 жыл бұрын

    How tight do you get the dowel rods ?

  • @nicolo2911
    @nicolo29112 жыл бұрын

    is it necessary to respect a certain gap for the piston ring? If so, how high did you set it? thank you

  • @rmatvmc

    @rmatvmc

    2 жыл бұрын

    Piston ring end gap is definitely a good thing to check. We have an older video showing how to measure piston ring end gap and adjust it if needed. You can check that video out here: kzread.info/dash/bejne/l5mgy9Obmpiql7Q.html

  • @Grimmi112

    @Grimmi112

    9 ай бұрын

    He did. ist at 11:57?

  • @WM_official
    @WM_official2 жыл бұрын

    How often need to do it just for casual riding?

  • @rmatvmc

    @rmatvmc

    2 жыл бұрын

    Follow the schedule in your service manual and do a regular compression inspection. It's better to regularly rebuild the top end in order to prevent the bigger and more expensive repairs. - Wes

  • @bradleyforsyth5032
    @bradleyforsyth50323 жыл бұрын

    Can you guys do a clutch on xr600

  • @natetwarog1938
    @natetwarog19383 жыл бұрын

    How do you know which piston size to buy? Size B, C, ect.

  • @owens5283

    @owens5283

    3 жыл бұрын

    Back of the cylinder had a letter on it

  • @owens5283

    @owens5283

    3 жыл бұрын

    Has

  • @xxgalaxymast3r421
    @xxgalaxymast3r4213 жыл бұрын

    do u have to have the torque foot pounds at the right foot pound or whatever or can u just put it on like a regular bolt?

  • @harpermx2962

    @harpermx2962

    3 жыл бұрын

    Just look up the torque specs in ur owners manual u don’t need the torque specs for everything but any motor work u do it will keep ur bike running better and longer

  • @ABM-BJ
    @ABM-BJ Жыл бұрын

    ❤❤

  • @Shadow0fd3ath24
    @Shadow0fd3ath242 жыл бұрын

    I always replace those stupid phillips head screws with regular bolts. Lot less chance of stripping them

  • @mozer30
    @mozer302 жыл бұрын

    Great video but I think you missed a couple of very important parts. 1. Unless the engine is on the first piston change you should always have the cylinder measured to ensure you purchase the correct piston size. Using a stock piston size on a worn cylinder is bad practice and defeats the purpose, as the piston to cylinder clearance may be at the service limit. 2. I’m shocked that the squish clearance was not checked, nor demonstrated. This is absolutely critical part of the rebuild, as too greater clearance will cause far from optimum performance, yet too tight squish clearance will cause detonation, resulting in piston, cylinder, and head damage in no time at all.

  • @Shadow0fd3ath24

    @Shadow0fd3ath24

    2 жыл бұрын

    When doing a stock size piston in a stock engine means you don't need to check squish. it stays exactly the same. That is a completely bogus and stupid myth

  • @redtobertshateshandles

    @redtobertshateshandles

    2 жыл бұрын

    @@Shadow0fd3ath24 just compare the two pistons side by side. You should do this anyway, regardless of squish.

  • @Shadow0fd3ath24

    @Shadow0fd3ath24

    2 жыл бұрын

    @@redtobertshateshandles of it's a stock piston theres nothing to compare🤦‍♂️

  • @Pumpkineater19

    @Pumpkineater19

    Жыл бұрын

    Nerd stuff

  • @devinn5306
    @devinn53062 жыл бұрын

    That took me 8 hours

  • @Berriesandcream56
    @Berriesandcream562 жыл бұрын

    If I'm getting a new cylinder, do I even need to mess with the power valves?

  • @kylebeach2316

    @kylebeach2316

    11 ай бұрын

    If theirs damage or signs of wear and tear then yes replace it

  • @dustin9035
    @dustin90352 жыл бұрын

    Did I miss checking the valve clearance and lash?

  • @rmatvmc

    @rmatvmc

    2 жыл бұрын

    No you didn't miss anything, that's an adjustment for 4-strokes. If you are joking with me, the comedy club has open mic night on Mondays at 7:00.... 😂 Either way I hoped this helped. Thanks for the support and let me know if you have any other questions! -Charles

  • @julianlaustsen1991
    @julianlaustsen19919 ай бұрын

    ur supposed to measure if the cylinder is oval and taper and the max diameter.

  • @jermained9874
    @jermained98743 жыл бұрын

    Can I have a 1994 yz 250 body and build a newer motor it it such as 2017 yz motor

  • @lucianoferreiradesa
    @lucianoferreiradesa Жыл бұрын

    👏👏👏👏🖤🙌🇧🇷

  • @charsiewestcott6419
    @charsiewestcott64193 жыл бұрын

    You were a bit blase` about the description of using the mid driven 12mm spanner with the torque wrench. I presume 22ftb at 90 degree but use formulae when using spanner in the straight orientation. Please be specific in future, you can confuse people inadvertently.

  • @redtobertshateshandles
    @redtobertshateshandles2 жыл бұрын

    I use EP transmission lube for assembly, I'm stingy.

  • @jonthelamb4549
    @jonthelamb45493 жыл бұрын

    I watched this then blew my bike up the next day

  • @Trucksims_500
    @Trucksims_5003 ай бұрын

    bad dont even have a bike