Well, after testing and going over every possability I still couldnt decide if my headgaskets were blown. I used a block check kit ( it uses a dye that changes color if combustion gasses are detected in your coolant) negative didnt change colors. Wouldnt over-heat trail riding all day, but would road riding. My engine ice had changed to a purpleish color... but I called the manufactor and they said that was normal because of the dye they used. If I ran the fan overide switch it would stay at 185 deg too with stock radiator. It did have some little black plastick looking peices floating in the coolant. Looked like a radiator hose was deteriorating some. So after second guessing myself I tore my engine down.. Sure enough both heads were blown! Looks like were they milled the heads from the factory it creates small lines that lead right to the coolant pasage. So I have sent my heads and jugs to be ground. I bet I will never have a heating issue or headgasket failure again. I also wasted my money on a PWR radiator. Because I ride with another 840 that has a stock radaitor with a dasa impellor and NEVER has overheated or got close. I wonder how many Teryx's out there are running with a slightly blown gasket and have been updating there coolant system and it is not the real issue. Again this was milled marks from the factory were they cut the heads. I bet there are alot of stock bikes out there with head gasket issues and the owners have no idea. Again there was NO coolant getting into my oil or into my cylinders and both heads were blown. Just a small amount of combustion was passing into my coolant under a load.. Like climbing a huge dune or hill and the temp would start climbing. Let it idle and it would get from 215 to 185:think: All this sounds like a common issue , espeacialy with 840 owners even though I dont think it is isolated to BBK, standard bore with the higher compression has the heating issues too. If I was doing one today I would pay the extra $180 bucks and have my heads ground and jugs right off the bat. Then for sure you wont have this issue.