I'm setting valve clearance on my '99YZ400 and I have a couple questions: I have owned XR's previous to the YZ and the usually course with XR valves was initial tightening from seating etc. then over time the valves seem to loosen. On the YZ I have noticed continued tightening: intakes .13mm X 3, and consistent tightening asymmetry with exhaust .13mm and .16mm (the latest). Is this normal,or should I see a loosening over time? The bike is very fresh and well maintained. With my XR, I would commonly set clearance at end range, predicting increased clearance with time giving longer duration in the spec zone. Can anybody with alot of hours and valve checks on their YZ tell me what to expect. Thanks, Keith.