98 Sportsman 500 has severe low RPM shimmy and pulls to the right. It will shimmy so hard that if you don't have a good grip it will pull the handle bars out of you hand.

I thought it might have been a loose wheel but that's not the case. Any ideas?

 

check the wheel bearings, check to see if that side is stuck in awd(it does happen w/ one wheel).

 

Change the fluids and try a 10 ft reverse with a turn, it usually will unstuck a stuck in awd wheel.

Here is a good link if you have to work on the hub.ATV Time :: View topic - Polaris Demand Drive Hub Q&A Picture Guide to Service

 

Outstanding article. I'll look into that and see if it will correct the problem. I also bookmarked this site for future reference.