I just borrowed this article from Team HIGHLIFTER, hope they dont mind...

Granted, they're selling something, but since this is the third time I've heard about it, thought it was worth mentioning here.....
MGJ
ISSUE!!! Sportsman 800 Plastic Melting
If you have ridden the new Polaris 800 Sportsman in hot weather, then you have "felt the burn!" Chances are, you are familiar with the EXCESSIVE HEAT generated from the exhaust. Heat that has sent some customers back to the dealer for replacement plastic. To date, we don’t know of any service bulletins that address the problem.
After a light-duty day of riding, we noticed significant melting near the exhaust on High Lifter's stock 800. We decided to see if there was something that we could do to help the situation.
Using two Polaris 800 Sportsmen, we devised a small experiment. Sportsman "A" was equipped with a lift kit, 29.5" Outlaws, Lift Springs, and a Temp Gauge. Sportsman "B" was BONE STOCK. Prior to the test, we wrapped Sportsman "A" exhaust pipe from the head pipe to the canister with High Lifter's silica impregnated heat wrap.
Both 800's were allowed to warm up to normal operating temperature on an 82-degree day. Temperature readings were taken along the exhaust and the side of the muffler with a digital infrared heat gun. We then made 10 slow laps around the High Lifter property. Next, we ran the same test on our oil additive "Motor Cool" and then our radiator coolant additive "Super Cool."
We discovered that, even in a controlled, light-duty test, there was a significant difference in the overall engine/exhaust temperature on Sportsman "A" compared to Sportsman "B." Temperature differences were measured IN THE HUNDREDS! Even with Sportsman "A" having oversized tires and lift kit, it maintained a significantly lower operating temperature than the stock Sportsman "B."
We are not saying that we have the ultimate answer to the heat problems related to the Sportsman 800. Chances are, you will continue to melt plastic until something is done to the design of the machine to change the situation. However, adding the High Lifter Heat Fighter Kit and Heat Shield Wrap will significantly reduce engine oil temperature, lower coolant temperature, and ultimately improve the quality of your riding enjoyment by
making the ride more comfortable for YOU and your leg!
Similar results have been observed in previous tests over the last few years on other makes and models. The severe problems of the Polaris 800 prompted us to see if these issues can be helped. The answer is yes. Call High Lifter Products, Inc. for Heat Fighter Kit ordering information today.
(Kit also available for other liquid-cooled and air-cooled ATVs)