My '07 700 efi exhaust gets so got it melted the plastic and the air intake temp sensor has it running horrible until it cools.  I don't pull anything, just ride. Has anyone else had this happen? Mine is over a year old, I wrote a letter to polaris to see if they will stand behind this since I met two guys on my last ride that the same thing happened to.  

Sounds like there is more fuel than air making it through and out the exhaust valve and burning in the exhaust. Try taking the airbox cover off, make sure your filter is clean and clear, and ride a little while.If that works, take a 2" holesaw and cut a hole in the lid where there will be clean air flow. It may be enough to even the mixture out.  

Just got a couple 500 EFI's in Jan. One has 28 hrs on it and the other has 23 hours (mostly hot flat land riding). Just took them to Colorado last week for 2nd Elk season. Easy to moderate climb. Very cool temps. Half way up the mountain, I smell plastic burning. Stop bike and pull seat. The entire right underside of the seat and right rear fender and the small quarter panel near the exhaust was all melted inside. Insulation tape did not appear to work at all. They both ran great. Engine never overheated.  My brother was riding my other EFI and guess what, almost identical. They are currently both at the Polaris dealer. I have not heard anything from them yet. Isn't that one of the main advantages of efi...fuel/air electronincally regulated, no removing air boxes or cutting holes, etc. As mentioned above, both of mine ran great. When my problem happened, I was only at about 6000 ft. Hed two older 500 HO's (non EFI)with us and they had no probs with bikes running lean or hot.