97 yz125 Power Valve

[jdc9q8]

I recently posted a thread involving a problem with the low end of a 97 yz125 and was told that the power valve could possibly be stuck open. Supposably I may have no back pressure at low rpm's and that it would run normal at higher rpm's. This sounds like what is wrong with my bike.

I was wondering where the power valve was..and if anyone could throw out some advice on how to check/fix a "stuck" power valve.

Thanks!

 

[NO HAND]

First, remove the pipe. Then you will have access the power valve cover on the cylinder. After you have removed that cover, unscrew also the PV arm so you can try and rotate the PV to see if it is stuck in one position.

 

[jdc9q8]

I'm assuming your talking about the exhaust pipe...PV arm???...if it is stuck in one position..how am I supposed to fix that so it doesn't continue to stick?

If there are any tutorials with pictures anyone knows about that would help...but if not this advice is definately helping..

 

[NO HAND]

Yes I meant the exhaust pipe. pv= powervalve

 

[TWRT]

It sounds like you should get a manual. I have worked on my bikes for thirty years, and I still pull my manual out from time to time. WWW.powersportspro.com will have full schematics for your bike. It may help you understand what No Hand is saying. It is possible that the power valve is so gummed up that it is stuck open. If that is so, I wonder when the piston/rings were last replaced?

Dave

 

[DLHamblin]

It sounds like you should get a manual. I have worked on my bikes for thirty years, and I still pull my manual out from time to time. WWW.powersportspro.com will have full schematics for your bike. It may help you understand what No Hand is saying. It is possible that the power valve is so gummed up that it is stuck open. If that is so, I wonder when the piston/rings were last replaced?

Dave

I agree; a severely worn top end can cause the dogginess described.