No power

Okay so i have a 2008 yz250 with low hours on it. Power valve broke had that replaced everything in the power valve moves as it should side ports main all that. The problem is when i took it out riding i have no top end power it just falls at like 1-2 to wide open just flat slower then a 125. I did reuse the base gasket because i didnt have one when fixed power valve before race. So could it be that im losing compression thats causeing it? The things i checked are power valve, reeds, carb everything looks perfect . Im so confused on this so any help is appreciated thanks

The power valve dont seem to open

take the exhaust pipe off and the side PV cover. disconnect the linkage. Just take the center bolt/screw out and gently pop off the lever. Take the PV shaft where the little bolt goes in and turn it fully each way by hand. Is it smooth? look up the ex port while doing this. Are both valves opening and closing together?

Thankss to Rjpjnk.. I just copy paste one of is post

Start to talk about the the power valve at 10:50

When I look up the exhaust port I can lift the linkage arm up and the exhaust ports all open the middle one and the side ones

With the linking arm still installed?

Ya could move it up to turn the power valve and it would open up

On mine I cannot move the PV with its arm attached. Mine is a yz250 '09

Think I have narrowed down to the lower linkage arm when bike is running "cover off" watch the arm and it doesn't move but can be moved up by hand manually

Yeah you need to pull the outer and inner clutch side cases off. The PV governor is not operating. Spring has problems or the thrust bearings that allow it to move.

found a pin in my oil... goes on the powervalve arm so should have fixed it waiting on gasket

I assume thats the pin that holds the governor together?

ya that is what i meant didnt know the name at the time when the power valve brok ein fall it must have compressed the governmer enough to pop that little pin out so it wasnt engaging at all bike runs great 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