I've never been into the starter on an ATV, only cars and a Polaris RZR, but the concepts have always been the same so I will take a stab at these possibilities:
1. You may have a bad "bendix" or solenoid or whatever it is that engages the starter motor's gear into the teeth of the ring gear or flywheel. So it may be sort of trying to engage, but does not have enough oomph to shove the gear into place.
2. You may have a bad spot on the ring gear or flywheel.
3. You may have a bad gear on the starter motor.
Regardless, you will need to at least take the starter motor out and have a look. I suspect you're going to find chewed up teeth and metal bits in there, to start with. You'll probably find more damage when you dig deeper.
1. You may have a bad "bendix" or solenoid or whatever it is that engages the starter motor's gear into the teeth of the ring gear or flywheel. So it may be sort of trying to engage, but does not have enough oomph to shove the gear into place.
2. You may have a bad spot on the ring gear or flywheel.
3. You may have a bad gear on the starter motor.
Regardless, you will need to at least take the starter motor out and have a look. I suspect you're going to find chewed up teeth and metal bits in there, to start with. You'll probably find more damage when you dig deeper.
