85 hours on my '07 crf450 and shes hard to start. valves have started to move and i see no point in shimming. it just delays the inevitable. i rebuilt my '05 right before trading it in on my current bike, and i went back all oem because i wasnt going to own it much longer. that may not be the case with this one. straight to the point, i am a revver. i ride my bike high in the rpms, always have, its just my riding style. what can i do to my valve train to make it more reliable for turning high rpms? ss valves? different springs? my plan is to buy an oem head (i can get them cheaper new, then to fix my old) and then lap whatever valves i get myself. also replacing piston\rings, etc and will have the cylinder honed (assuming it is within spec) im looking for solid professional advice only please, thanks.