power valve help....

[reeseyz125]

ok i have a question about the power valve and the seal for the linkage. i was told that a bad seal can cause an air leak which messed up my new piston. eventhough its sealed by the cover with a gasket and the power valve cover is bolted down with gasket as well, can i get an air leak? not only that, they say that the rings in the pipe can cause that as well. is any of this true? and what should the piston look like from an air leak? im doing another top end from the likes of this, but i figured it was caused from me being in 6th gear for so long wide open. i know stupid right? this is my first bike and im learning the do's and dont's. and right now im finding out alot of dont's.lol.

[MXtras]

I don't believe a leaky powervalve seal will cause that much of an air leak because it is covered into a sealed and gasketed chamber, so for that being your problem I say probably not.

Now, the rings on the pipe - absolutely. The head pipe needs to seal completely otherwise you will suck air.

Scott

[reeseyz125]

THANKS MXTRAS, thats all i needed to know. now i can put my bike back together. this site has been so helpful, im glad i joined. but i can bet that ill be back with more questions,lol.

[cetanepusher]

Originally Posted by MXtras

I don't believe a leaky powervalve seal will cause that much of an air leak because it is covered into a sealed and gasketed chamber, so for that being your problem I say probably not.

Now, the rings on the pipe - absolutely. The head pipe needs to seal completely otherwise you will suck air.

Scott

Rings on the pipe, I'm lost here, do you mean the sealing ring on the exhaust pipe where it sits in the head?

[reeseyz125]

he means the hi-temp. rings that go inside the tip of the pipe. they look like large O-rings.

[cetanepusher]

My 95 YZ250 has a FMF Fatty pipe, and only uses 1 O-ring. It's in great shape and seals well.

However, the connection to the rear muffler is questionable, but i was informed to get a piece of high temp heater tube and clamp it over the connection to avoid leaks.