I just bought a 2006 Artic Cat 500 (575 miles). It ran great when I tested it. Brought it home rode it fine. Added some gas, pretty sure the gas was good. Ran good, then all at once starting stalling when trying to open throttle and take off. Have to play with throttle to get going, still never makes any power. Idles okay. When throttle is increased is bogs down and backfires while in neutral. It is carbuerated. Is there an automatic electric choke? It does start good. Is there a safety devise that kills the spark if a sensor thinks the atv is in reverse or some other gear? I had a 2 wheel drive Polaris once that the reverse shift lever had a sensor on it that limited the engine power when in reverse. Had to wire around switch to get bike to accelerate.