I bought a 2004 WR 450 recently and am going through it. Sorry for the lack of knowledge however, I need some info. I went in and checked the gap on my valves and they were tight so I loosened them up using this site and the manual. What I need is some knowledge. Why, how does the bike run if the valves are tight and or if they are loose? Also, the whole timing issue. while I was assemblying, the chain slipped so I had to to the timing thing from scatch. I lined everything up, again using this website and the manual, got it back together and it fired up and ran but I was very concerned that my cams may have been one pin out when I reassembled based on looking at the lobes. How would it run if it was one pin out? I just need some basic engine knowledge! I have replaced the exhaust with a FMF Q4, sent the carb to Zip-Ty for a rebuild, installed a scotts stabilizer, put in a rekluse z-start pro and left hand brake all over the course of a week. Should run and feel like a new bike when I am done. Problem is I don't know what a new bike is suppose to run like!