They rebuild those bike after every race because the compression they run which is rumored to be well over 14:1, and all they do is replaced the ring and piston regardless of waer. all other internal parts are replaced as necassary. MC's tranny cost 25,000 cuz of the man hours that were put into it, there is no way that a dirtbike tranny could 25k in materials alone. I mean think about, he is worried about hiting the rev limiter, but if you pull in the cluch with the throttle at wot with the motor at redline ur gonna hit rev limiter anyway. And I did not comment in any way that using the rev limiter to shift would be OK. I simply stated that the rev limiter is there to keep the engine within its design parameters so that it does not catostrophically fail if the rpms spike to 15,000.