This is a common problem with disc brakes. I have a 98 Sportsman and my son has a 98 Wolverine they both squeak after sitting for a while. It is a combination of a thin film of rust forming on the disc and dust. It's no big deal just ride and apply the brakes lightly for a while until it goes away. Works for me.

 

Hey guys I have a question.. I was thinking of purchasing a wolverine.... I want a fast quad I can cut up on and still use as a utility..I thought that it would be perfect... But it sounds like that it has a few problems... Is this just a piece or should I buy one?.. Forgive me but I have never owned a yamaha...not cause I didn't like them just cause I was used to others... Is it trustworthy? the big question...
Thanks Jim