I finally had to shim my right in-take valve. After studying the posts on the topic, I am wondering how long the stock valve is likely to last now that it has moved. My bike is a 2004. I am a recreational rider, so I don't run at really high rpm all that much, and I don't get a ton of hours on my bike (unfortunately). I would guess that I have just over 100 hours by now. I had been checking the valves about once a year, and they hadn't moved as of my last check in 2006. In 2007 I had a dealer check them and I thought they changed the shims, but they didn't. Maybe they didn't even check it??? But on my last trip the bike became extremely difficult to start, so I checked the valves when I got home. The right in-take was down to 0 clearance. I replaced the 192 shim with a 170 shim and I am now back at spec. Some of the TT posts indicate that once the valve starts to wear, it will require re-shimming more frequently or require new valves soon. So, based on my riding profile, how much life should I expect from my valves and current shim setting? I bought the shim kit, so I can change shims as needed, but if it requires changing frequently I would just as soon replace the valves. Or am I likely to get another 4 years before needing another change? My current plan is to run the engine with the 170 shim until it needs to be changed and then just replace the valves. Is that a reasonable plan? Or should I continue to replace shims? Or should I replace the valves now to prevent damage to the head? It seems that the general preference for replacement is to move to stainless steel valves. I assume I would replace all four valves as well as the springs. True? Should I also replace the cam? Do I need to replace the head? Thanks for any advice.