I have replaced , kill switch, ignition coil, trigger coil, stator, voltage regulator, battery. I was getting an intermittent weak spark. NOW. I bought a used wiring harness but it looks slighttly different. Has a small black box on the wire from an atv wrecker. 2×3×1 inches about. Is this from a different year? Its missing the black wires on the igntion pig tail that goes to the throttle cable. Early vs late 2003 maybe? Anyhow wondering if i can make it work. Are all 500 engines the same mechanically? Hypotheitcally if its a newer wiring harness could i convert it? The old wiring harness is corroded and i have new wiring issues with it every year lol.... looks in way better shape.

 

Anyhow i sent this harness back and bought a brand new oem harness thats year specific out of luck. Still no/intermitten one spark. I added an extra ground from frame to engine. I made sure battery was charged. I put a spark plug boot and wire on from a car because the one in box was too short with ignition coil. Still no spark. I think if the flywheel doesnt do it its probably a bent flywheel or worn out magneto bearings as per the manual states. Thats alright im restoring the quad. Anyway just hoped to get it going for hunting season