I bought a z440 the other day and it ran great no problems. Got it home went out for a ride and than it started backfiring. It idles fine and runs fine until you throttle down. Then it backfires a few times than it seams like it has little power and won't build up speed. I put new plugs on it. The key switch was disabled, only the kill switch is used. Idk if this matters but hand warmers are weak and don't get very warm at all.
1999 Arctic cat z440
