Re: stumble ZL500
you could have a cracked reed take them out and check carefully. also your needle could be to rich. there are 5 settings in the top of the needle. i'll bet yours is in the middle. take the tiny e clip out and move it up on the threads to the no 2 pos. make sure you only move it 1 space at a time, and check your plugs at 3/4 throttle. to check at that stumble point go in a field and run it up to where it misses, as soon as it misses hit the kill switch, but dont let go of the throttle. keep it held where it was missing and that will tell you if your sled is to rich in that part of the power band. use new plugs get ngk v grooved series you can read the plug alot better. you might have to do this a couple of times to get the plug wet. GOOD LUCK