Ok folks. I have a few issues with this bike, and it's driving me insane. History-1990 DR350s, always been a bear to start. 137.5 main jet, 42.5 pilot. Cleaned the carb more times than I can count. Would love it to start well-but that's not my real problem. I cannot get it to run well consistently. It was really boggy in the low end of first second and third gear. I have tried adjusting my mixture screw multiple times-from 1 to 3 turns. Bike would run great for a few hours, then would start bogging down again. I decided to adjust the valves. Before I did this I was running about 1.5 turns from seated with the mixture screw. After adjusting valves the bike was running very lean-now I'm out to 2.5 turns. The rpm's hang horribly-unless I turn the idle screw out to the point where I'm almost stalling. This doesn't completely solve the problem however. If I accelerate slowly no problems, but if I open up the throttle I get very high rpm's with very little acceleration. Vacuum leak? The petcock is a raptor petcock, and the old vacuum line is capped. the previous owner had cut out the top of the air box (The jets are slightly larger than stock-but not as big as Jesse had recommended for the air box mod) and I've run it with the top removed and in place-same results. Seems I can get it dialed in, but after a few hours of riding, she regresses. I'm throwing myself here. I'm no mechanic, but I am capable of doing the work, apparently just not diagnosing!! going to look for vacuum leak tomorrow, and I have an extended mixture screw on the way so I can adjust the mixture with the bike running (it's impossible to be precise with the stock screw unless the carb is off) anybody have any other ideas??