Im going to just bite the bullet. and by a new caliper and all new brakes and rotors. I just got 500 in the atv. it runs great beside the brake issue

 

Main thing that wears on the calipers is the pistons and seals,kits are available,but if this is the way you want to go best of luck. If the rotors are scored,than yes replace them while you're at it. Afterwards no more brake worries. $500 for a running atv isn't too shabby.