ORIGINAL: JimTrainor
Why do people here beleive that a 4 stroke should run below 10K ...
I find it somewhat arbitrary, and nobody ever gives a reason for the supposed 10K limit ???
It has something to do with valve train limitations. Some valves start to float above 10K rpm. However, the YS 63 runs the best between 10.5K - 11.5K rpm without fear of valve train failure.