just acquired a 98 sportsman 500, trouble with the carb I think. Idles fine, but stumbled badly on the throttle and no accelleration. Turns out the airbox lid wasn't sealed so I fixed that. The bike then would accellerate, but at 1/2 to wot it still stumbles and misses. I disassembled and cleaned the carb, checked float level,checked all jets, set idle mix at 2 turns out, checked all boots for leaks... same problem. I moved the needle clip from #3 to #4... no better. I even tried unhooking the throttle switch and used the override button as described in other post but no difference. I'm sure its gotta be carb related. It accellerates hard off idle but falls flat at 1/2 throttle. It has stock jetting by the way. Thanks, Clark

 

Hmm is the opening in the air box clear for air to flow in also maybe check your vent line for the carb as well as your fuel tank. My line on my tank was pinched under the headlight pod and it was not allowing the tank to breath. Sounds carb related though. Maybe there is a rip in your diaphram or your slide. Did you check the air jet in your carb.. Check the fuel level in the bowl when it is running.

Probally something simple.

Erik trailblazzers@shaw.ca