i have cleaned the pipe, taken off the cylinder and checked it, and taken the carb apart at least 4 times. It all looks very clean and in good condition. my problem is that sometimes the bike dosent seem to be reving as high as it should Normally, i can get it up to like 30 mph on flat fround, and it revs like crazy. But the other half of the time, it doesnt rev quite as high, and only runs like 20-25 mph. when it runs bad, it will rev, and then the revs drop a little, then it will pick up a little, and then drop off again. This cant have anything to do with the timind, points, or any part of the ignition, could it? what else could it be????