I've got a big problem, and it's been keeping me from riding this summer, so any help would be awesome. When first kick the bike (98 YZF400) it idles just awesome, but when I start moving (or just twist the throttle) the bike loses a SUBSTANTIAL amount of power. So much in fact that it hardly pulls me on flat ground. The bike Backfires, and bogs, and even burnt my White Brothers pipe to a crisp. Here's the thing though! the bike runs like BRAND NEW every 25 or so times I start it up, but if I turn it off it will almost always go back to it's poor performance. The first time it started doing this was after I did a run up Chokecherry hill at St. Anthony Dunes in Idaho and turned it off. After 2 times of kicking it over it ran great the rest of the day. Now that I'm back in oregon it hasn't run. At first I thought that it was a simple dirty airfilter, so I cleaned it. Still ran like crap. Next thing I did was clean out the carburator... a few times. Same thing. Next I got into the head, checked the valve clearances, adjusted the valves (one intake was a bit off), and noticed that the timing was a little funky. The actual cams lined up with eachother, but the H shaped timing mark on the flywheel was off by a few degrees, so Rotated both the cams counter clockwise one tooth. Now the timing seemed to be closer (on the other side of the timing mark) But still a little bit off (stretched Timing Chain?). So Decided to put it back together, and take it on the street for a test run. The bike runs AWESOME! Better than EVER! I pull in the driveway, turn it off, come back not 2 minutes later, and guess what... It's got the same problem. not too thrilled about riding the 400ex around while I know a perfectly good (sometimes) YZ is sitting in the garage. Please help me diagnose this problem!!!