2008 YZ450, runs great and I maintain it very well. OIl changed at 10 hours max, usually at eight hours, fresh airfilter every ride. Bike has 452 hours on the meter. I put a new piston & rings in it about 200 hours ago just for the heck of it. I don't moto the bike but I ride/race offroad pretty hard. About the only issue with the motor is that occasionally when kick starting it will not build pressure when trying to find the compression stroke with the kick starter...so maybe a sticky valve? Valves clearances are all in spec.
So my questions are 1) should I plan on replacing the valves, and 2) should I start thinking about rebuilding the bottom end just as preventive maintenance?
I've read through this thread http://www.thumperta...cked-her-up/?hl= crank shaft and it looks like it contains a pretty good parts list.
Also, can somebody recommend a good source for OEM parts?
Edited by Wiz636, December 07, 2014 - 08:44 PM.