I have been reading through the posts and wondering about when it's time to rebuild the motor. I see a lot of folks have rebuilt the motor on their older YZF's and was wondering if it was due to lack of performance, starting issues, or is it preventative medicine. I have a 2002 426, and I ride a fair amount mostly trails and desert, with the occasional trip to the track. I take good care of it with regular oil and filter changes and valve clearance checks. It is super reliable and starts up first or second kick, valves are in spec, runs strong, etc. Should I be considering a rebuild anyway just due to the age of the parts? I was just wondering if the motors need a rebuild after X hours, or what the deal is? Thanks!