I purchased a 2002 crf 450 about 6 months ago. i got a pretty good deal on it because it was in parts and missing plastics, chain, sprocket, etc. Once i got the bike put together it ran, but i started having serious popping when i would let off the throttle. I torn the carb out and rejetted it for the altitude and temp... problem still exsists. I've been reading up on this bike and i've heard that valves can be a real issue with this particular year. Any thoughts on what might be going on? Also, the throttle sticks open. As you can assume that is pretty scary. i replace the throttle tube and cables and it got worse. now i can hardly twist it. I've looked over the throttle components on the carb and they appear to be working smoothly. Any thoughts there? I'm starting to get pretty frustrated with this bike and i'm outta ideas. :bang: