Thanks for the answer dude. The problem was and still is uneven rpm, studdering between 3000 and 4000 rpm. What I suspect is overich fuel, too much fuel. I played with the fuel petcock, moving it towards the off position. It leaned out the mixture and that improved the problem. This bike had a 4 into 1, and was probably rejetted. Is there any way to know if the jets are factory or aftermarket??