I have a 96 Sportsman 500 -will idle fine just has no power . Bought it used, never seemed like really had that much power always lost it on the topend, or just going up hills etc, but got worse. So at first thought must be carb! so took apart cleaned it (many times), diaphram was marginal so replaced it, fuel filter replaced checked all vent hoses air box for leaks etc took fuel pump apart there was plenty of dirt on the vent side cleaned it, thought that must be the problem, but made no diference. tried another carb off another machine ran the same! so since then!

1) tore it down checked exhaust lobe was within .001 of new dimensions, rocker arm looked good no unusual wear.
2) pulled the black wire off limiter like u suggested above no diference.
3) made sure elc throttle control was not causing problem.
4) tried pushing reverse bypass switch while acceelratings no diference
5) tried putting on choke while accelerating, wanted to die then.
6) sprayed carb cleaner around carb while running checking for leaks no diference.
7) ran fuel with a direct line from gas tank to carb by-passing fuel pump made no diference.

Anybody else have any other ideas please tell me!

 

it just sounds like the cam but you checked the exhaust lobe.??? i would check the cam again..if that dont work try the stealership route