its a 70cc 4 stroke chinese quad it ran fine for a while one day he rode it shut it off and tried to start and the startor just spins, so i took off the side were the stator is and the startor is hooked to a chain that runs to a sproket behind this pulley and it just turns the chain but does not turn the pulley dont know anything about these quads please help,how to take the pulley off to see why the sprocket with the chain to the starter just spins.