I just picked up a used Sportsman 500, 98 model and when going slow the front end kind of lopes.
This is hard to put in words, but basically it feels like the front end is making a circle. Once you
get over say 10 mph it's as smooth as it can be. I jacked the front end up and spun the tires and
they spin perfect. Any thoughts?

 

Give us some more details about what it does. jack up the front and push and pull on everything. Check the orange spacers/bushings on the a-arm. Maybe alot of slop?
later

 

Jacked it up last night (all 4 wheels). There is a little slop side to side but I don't think it's excessive.
The front shocks are toast, so I'm wondering if that might not be the cause. Also found out that
one front tire is not engaging when put into 4WD. Pulled the hub apart and found that it was basically
dry, and that the magnet is not strong enough anymore. About half as strong as the other side.
This is turning into a real money pit. Should have kept my trouble free 350 Yamaha, but NOoo had to
have more power. Not bashing Polaris, it's just looking like this particular one has not been taken
care of.

 

If the bike sat a while, the cords in the tires may have a flat spot in them. My bike does this sometimes if it sits for a while w/ low air pressure in the tires. Just a thought...