I gave my 636 motors hell via rev limiter bouncing in the stunt bikes...They would last me 1-2 seasons, and Ive only actually blown 2, Ive been through about 5 but others were due to the cylinder head cracking from crashing, not the actual motor blowing up. Swap the head and the bottom end goes for another few rounds...
I just started to convert my 09 over to my full time stunt bike, I brought it to the practice spot twice. Half an hour into my 2nd session on it and I spun crack bearings......This does not look good for future reliability, I have a bad feeling Im going to be popping these motors on the regular...