I will be driving along on my sportsman and all of a sudden it will start pulling hard to the left or the right sometimes when I back up it will straighten back out, and sometimes if I engage the 4 wheel drive it will help, No cracks or damage to the cv boot, and hub oil is good. What is going on here. Anyone???

 

sounds like a wheel bearing or axle bearing is binding up. Jack it up and turn the wheels by hand 1 at a time maybe it will show up.

 

Usually it's the armature plate that has become magnetized that causes this. Especially if in two wheel drive and one side kicks in. Usually releases when you back up and go forward again. This can happen over the years or even quicker if people leave the awd switch on constantly and current flow to the coil magnetizes the plate. It can be dangerous if not addressed fairly soon as I've had some that engaged at higher speeds and a little unnerving to say the least. I'd replace both armature plates as usually the other side will do the same fairly soon. Current to the coil can magnetize the plates. Plus when you have the hub off you can check out the bearing,roll cage and coil sleeve face for excessive wear also.The hub nut must not be torqued over 12 foot pounds. When torquing the nut if the cotter pin holes don't line up you can back the nut off a tad to where it does and won't hurt.Item #4 on the parts break down. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

Thanks for the info will check it all over.