Power Valve......Part?

Hey, guys.  I'm new to TT, but have used it as a reference for many years.  Lot of good stuff from a lot of crafty folks. 


The other weekend while racing MX, my lovely(13' YZ250) started running like crap.  No low end power, very hard to keep on the pipe, and sounded like the exhaust was made out of a soda can.  I knew it wasn't the piston or rings.  Compression was about 230.  So I figured the power valve.  As I removed the side cover to access the power valve push rod, I noticed the hole for the dowel pin did not line up with the hole in the cylinder.  I was afraid it was bent.  Long story short, the little clip thing in the photos had popped off of the top of the main valve, and got lodged under the cam for the sub exhaust plug on the left side.  Not allowing the valves to completely close. 


My question is: is there a way to secure that piece so it doesn't pop off again?  I realize it has a "holder" on the shaft, but it let it pop off somehow.  I thought about gasket maker or thread locker.....but I'm not sure how it would do. 


If nothing else, maybe sharing this will help a two stroke brother sleep soundly.  I lost many nights of sleep worrying what it could be before I tore into it.  haha





photo 1.JPG

photo 3.JPG

photo 4.JPG

photo 5.JPG



I have broken many. I just remove the old part and let her rip


Good thread.  Wish I'd seen that sooner.  I already put it all back together as it should be.  If I have any other problems I will probably do as you suggest. 


You would think with so many people having issues Yamaha would address it.  Oh well.  No big deal I guess.  Rock n Roll!

 I'm emailing about a problem with my 2013 yz 250 2 stroke, i bought the bike from power sports junction back in 2013. so far i have put 15 hrs on the bike. Last time i was out the bike started acting up, weird noise at idle and lack of power. Myself being a apprentice motorcycle tech i investigated and found the issue to be a broken power-vavle. The stopper on the end of the power valve had broken off and lodged it self to prevent the valve from fully closing. The fix it self is not a big one but the part 5XF-1131D-00-00 is very expensive. I know that it is a competition machine, but this seems to be a part defect. I hoping you can help me with this issue. I'm a big Yamaha supporter and all my power-sports are Yamaha. (nytro,r6,yz250) . Thank-you for any-help in this matter


There Reply 


Good afternoon Scott! 

I appreciate that these are difficult times. I am afraid that there is no warranty on this unit. It's simply impossible for us to consider the failures related to a manufacturing defect. I'm afraid that all vehicles require maintenance and servicing and after this many years you will need to replace and repair components. I did check to see if there is no outstanding recalls, bulletins, tech tips or reports that would have allowed me to participate in the repairs mentioned however there is nothing. 

It is always difficult to say no to a loyal Yamaha customer but as a manufacturer we need to strictly treat all customers equitably and participating in repairs on units outside of the warranty period is just not fair to all owners. I hope you can understand our position. 


480 Gordon Baker Road, Toronto, Ontario, M2H3B4

T 416-498-1911

You got pretty lucky most of them break off, here in canada Part # 5XF-1131D-00-00  is close to 300$ i feel sorry for people that cant repair this themselves or just keep riding the bike unknowing of the issue.

Edited by scott-h-1992

You got pretty lucky most of them break off, here in canada Part # 5XF-1131D-00-00  is close to 300$ i feel sorry for people that cant repair this themselves or just keep riding the bike unknowing of the issue.


Holy crap!  That's pretty steep.  But yeah, it didn't break.  Just popped up and off the valve and got lodged.  I did get lucky, though.  I raced 4 motos with it lodged in there.  Lucky it didn't bend the shaft or anything else.  But she is back together and running flawless now.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By neonmarine
      Hey guys, 
      I've used this forum as a "guest" for awhile now and I thought I'd share my build now that it's all coming together.  The primary purpose of this project is to help me train for roadracing my 2009 R1 at lower speeds as well as giving me a cheap alternative to racing the big bike. 
      Here's what she looked like when I picked it up from a local shop.  Paid $800 cash for the bike as you see it with 17' rims, FMF pipe, EBC 250mm front rotor and clip on handle bars.

      Fits PERFECT!

      Shake down run at the Herrin Compound last summer:

      As she sits today:

    • By 125 yamaha guy
      i bought my yz125 from a dealer and they said that the clutch was broken so i bought it and it worked fine it would run move and everything and then it started to act up and now only first gear works barely though. when you put it in first it acts like its bogging down but its not and when you go into gears 2-5 it wont move i dont know whats wrong with it im assuming the clutch is slipping or something if you know please leave me a comment 
    • By Randomneewb
      Hey guys, I have a 2003 cr125 I bought a couple weeks ago and I'm having a problem with it. The spark plugs die every about 15 minutes, with hotter plugs it will last about 45 minutes. I herd that if the timing is off it can over heat the plugs and burn out the the resistor. Is there any truth to that? The reason I thinks it's not fouling is because when the plug dies it gives no spark no matter how much you clean it, And it shorts out. 
    • By fiat2nv
      Hi all, First post here. I need some help.
      Ive just bought an 05 yz 125 for a good price but it needs some work. One of the forks has some pretty severe pitting of the chrome on the stanchion towards the bottom near the brake caliper mount.
      Ive found a pair of good condition forks from an 04 yz250 for a very good price, from the research ive done its seems that both the 04 & 05 forks are 48mm but are different, with the 05 fork regarded as being better than the 04, but not as good as the 06 + sss forks.
      Im looking for the cheapest way to get me riding, Will I be able to make the 04 forks work with my 05 triple clamps, brakes, wheel, axle, spacers etc? If not does anyone know what hardware id need to make it work?
      Finally, as a last resort, does anyone know if i could swap the stanchion from the 04 fork into my 05 forks?
      Thanks, Andrew
    • By idratherberiding
      I bought a 2006 YZ250, have ridden it 5 times.  It needs some tuning, but I am not sure I'm keeping it so don't want to spend much on it.
      Has fmf gnarly expansion chamber and turbine core silencer.
      I ride about 1000 feet above sea level.
      I'm going to clean the carb and check the jetting.  What is a good jetting for me?  85 main jet?
      Also check the reeds.  Is there a big difference between getting aftermarket reed cage and reeds or just getting a cheap aftermarket set of reeds that fit the stock cage ie.  Boyesen Power Reeds?
      The other things I'm going to do is permatex all the joints in the exhaust system and a compression test.   It was 220psi 5 rides ago so I'm guessing itll be fine.  Its bogging a bit but I'm thinking its carb and definitely exhaust joint related.  
      Let me know if I'm overlooking anything that could make the bike run crisper and more bottom end without throwing much money on parts