The other day I was riding on my motocross track and coming out of a corner while I was getting back on the throttle my bike just lost all power and bogged down so I hit the kill switch. When i tried to kick the motor it was super hard to kick so I hauled it back to the shop took the valve cover off timing was ok, cam chain was ok, and valve clearance was in spec. I turned the motor over by hand it seemed ok so i tried kicking it again and it kicked fine until it finally fired, which it took forever to do and it usually starts on the 2nd kick, it bogged and died and was hard to kick again. I have both side cases off the motor and everything seems to be fine so far. I just rebuilt the whole motor probably 20 hours ago and did not replace the crank because everything was inspect according to the manual. What do you guys think?