A buddy of mine has a 2000 WR400F and just replaced the clutch plates (just the fibers) at the beginning of the year because of slippage. Well it is doing it again. Should he have replaced both sets of plates? His valve need adjusted bad. Would this have anything to do with the slippage when he gets on it. I rode it last night and when you give it a lot of gas the engine just revs high and you go no where. Could this be a tranny problem too? Please help!