Keeps jerking when in auto gears

Have you tried to lower the idle? When an Auto/5speed shiftable transmission is stopped in gear the drivetrain holds it back or loads it down a bit. If you take off a load the idle will rise. Sounds like your idle is too high. Do you have your idle set high to keep it from stalling?

if its been stuck a long time (which sounds like a good bet) its going to take some force to get them off. maybe bolt a chain to the hub studs then swing a sledgehammer attached to it to jerk it off. if that model has adjusters (think its automatic??) back it off or there might be a button you push behind the rubber plug to release the auto adjusters.

On some ATVs there is a module on the side of the transmission/motor that will go bad and cause it not to shift. I would check it out first.

Hey Anon,
This sounds very serious..Unless you are a VERY GOOD mechanic, you need to take this machine to a qualified professional..it will be best in the long run...

Geez dont keep spending money if your not sure. It sounds like your starter is not throwing in far enough to engage with the ring gear. Please do your hip pocket a favor and get an auto technician to check it before buying a new starter as well. You can also remove the starter and check the gear to make sure its not worn as some are plastic.

Repeat the process with a manual. Sounds like shaft not engaged.

Spark timing needs checking.

Check the gear change lever where it joins onto the side of the engine/gear box. Could have slipped off or stripped the splined shaft. If that is fine and when you move the hi/lo range, and the shaft on the gearbox moves its possible the gear change mechanical levers have broken on the inside of the box.

Sounds like clutch adjustment will see if I can find directions