I have an 02 426 and put a Thunder Alley pipe on it awhile back- love it. I rejetted it as recommended and it seemed to be running fine but the idle was a little low so I adjusted the throttle stop screw, seemed perfect after that. Next time I tried to ride it up the street it ran like crap. I can't seem to get it dialed in right. The manual says set the pilot screw to 1 3/8 turns but says nothing about setting the throttle stop screw (the one with the plastic knob on it) after you screw with it and mess things up. I called the local Yamaha service, they said out 1 1/4 turns on the throttle stop screw. I haven't messed with the pilot screw at all. Now it kicks back when I try to start it. I could use a little help here!