I have an 2005 sportsman 500 ho, and I was riding it this weekend and it overheats. The radatior is full and not pluged and the fan was running.

 

Are you positive it actually overheated? The indicator would give a false alarm on some of the 05's. You can do a search on this forum to see what others have discussed.

 

Are you sure rad not plugged? It can look clear from the front but be plugged up in the rear where it builds up against shroud also washing it from the front forces the stuff to the back fins.

 

Yep, what he said. The best thing you can do is twice a year remove your fan, then your fan shroud (only four bolts each) to get behind the radiator and wash it from both front and back. I can have the two pieces out of the way in about as much time as it takes to jack up the machine and take the front wheels off. With the wheels out of the way you can get in behind the radiator better. The fan and shroud slip out through the right side. Well worth doing.