Also if you bought yours new, between August 2004 through February 2005, you should know that Polaris did a 45,000 unit recall.
Here's your general troubleshooting tips for overheating...
If you are running lean, your engine will run hotter, have you opened up your intake some how, & or added or modified your exhaust, without rejetting
If your radiator cap was not tightened to the 2nd notch, or your machine has gotten hot enough to warp the filler neck, or there is some other issue that keeps your cooling system from building pressure, your engine will run hot...
If your thermostat has stuck partway between open & closed, you'll run hot...
BTW... even if you think you have your radiator clean, it's nearly impossible to get it fully clean, with out removing it... I like to use a waterproof flashlight one one side when I'm cleaning, to better see through the fins... some types of mud, will leave a film on the radiator that insulates it, even if it looks clean... lots of people have started using "etching" type mag wheel cleaner to remove this film... with good results ( I personally wouldn't use it too often however, as "etching" types of cleaners may eat through the radiator after lots of use... some have started using a "pitch blend" cleaner / sealer sprayed onto the ATV to keep things from filming up, after they have cleaned the radiator with the etching cleaner...
Good luck.
Let me know how it turns out.