I recently bought a 99 WR400f about three months ago. The guy I bought it from claimed that he only put 400 miles on it, which I kinda believe because it had the original tires on it with good tread left, and the grips were original in perfect condition. It has a header pipe and exhaust , been jetted, but he had not done any of the mods. I took the small airbox cover off, throttle stop, and yes the grey wire is still connected(still confused about how much good this does for your bike vs. the power gain. So far I have been out like 8 times on it, and it runs like a champ. Faster than all the other bikes I ride with, (05 WR450 all plugged up, 05 KTM 400EXC, Jet and Pipe, 03 CRF450 Stock) and it seems to run perfect. My question to all of you is when am I going to have to get in there and look at the valves? How will I know if it needs an adjustment. After looking at countless post's on here I have come up with a couple of different ideas of when I think I need to do it. I just want to hear it again from you guys. I know that there is a risk of running them till they get too tight and burning them, but when I see guys post things like 8000 miles or more before they ever get into the motor to see whats doing. And others post they get in there and look at them every other ride, I dont know who to believe. I am not a throttle happy person, and dont rev the bike out too much. I change the oil every other ride, as well as clean the air filter. I guess I really want to know is when will I know when I have to get in there? Is there anything besides power loss that will give me a good idea they need adjustment? As always the more feedback the better. Thanks all.