I hear you check the valves on a 4 stroke for wear and stretch. I bought the bike used so I don't have the first idea how much they have stretched from the start, just that, with a feeler, they were in the legal range last time I checked (cam change, -legal before and after). I plan to pull the head off and inspect the valves. I also plan to replace the timing chain and probably the valve springs on the theory that preventive maintenance will save me big heartache later. She starts easily and runs clean up and down the range. The questions are: 1. How do I look at a valve with unknown history (except my year of riding) and tell if it needs replacement? Am I looking for wear on the valve face (they're titanium with a coating). Is there a stretch limit I need to worry about? 2. Assuming I find a mess, has anyone switched to stainless valves and found they induce valve float at a lower RPM? I trail ride the girl and don't rev it high much, but occasionally I do. 3. What fails on the bottom end? Time for bearings? (3 years on the bottom end). Thanks in advance.