New Piston Rings/Front sprocket = no power?

Joined
Sep 11, 2001
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#1
Just rebuilt my top end in my 98 yz 250 put a 15t sprocket up front and bike doesn't seem to have much hit in the mid/high dept. The bike sounds extremely crisp and bottom end is pretty strong but when I get on it the bike sounds muffled not allowing any over rev at all, wondering if the power valve could be the culprit? This is the first time I have rebuilt this bike and not familar with the power valve. What could I have missed. Went off the book and wondering how can I troubleshoot it? I really believe this to be the problem just need to know where to go from here. Thanks
 

rickyd

Hot Sauce
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Oct 28, 2001
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#2
Did you install the piston in the correct direction??
 

Rcannon

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Nov 17, 2001
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#3
What rear sprocket are you running? The 15 on the front is two teeth larger than my 1997 YZ calls for. This might explain the lack of hit.
Did you try to cycle the powervalve through it's range? It is easy to do from the right side of the bike.

Top end power on my 1997 model is nothing special, bu tit is there. Is your bike less powerful than before the rebuild?