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





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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.

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