I just bought an 01 YZ426 and was not in love with the way the bike started. I have read all the threads and know the correct procedure but still not satisfied. It seemed like it was time for a carb cleaning and valve check. The problem I am running into is apparantly the prev owner bashed the left side of the motor because the crankcase cover is aftermarket. This wouldn't bother me normally but there are no plugs to access the crank bolt or view the timing marks. Any suggestions????