I have an 04 that only gets trail riddden. Well maintained. When the valve train does go and needs replacing what should I do: 1. Replace with full OEM parts (springs valves etc) or 2. Use KW or RHC parts? Reason I ask is not for problems with longevity of OEM parts but performance effects of fitting the heavier stainless springs and valves to the lightweight CRF motor. If I am prepared to accept the valve train replacement frequency of the CRF then should I stick with OEM? That's what I feel I should use. I think I will also replace the springs well before any valve tighteneing occurs as they seem to be a massive part of the intiial valve tightening process. I have no problems at the moment. The bike is new. When the time comes I just want to know what to buy. OEM appears perfect for my needs. I dont race, I just trail ride very mildy, the motor is unmodified and I have extra oil capacity fitted. To me fitting a heavier aftermarket valve train would appear to be overkill as I am simply not wearing parts out that quick. Are there any other benefits of fitting aftermarket valve trains that I have missed? Guru advcie welcome!!!