I have a 05 WR450, that upon startup gives off an odor which suggests anifreeze is burning. I don't seem to be loosing coolant or very much, like I haven't had to add any to the recovery tank, and the suspected leak isn't external. So I was assuming a possible head gasket leak. The local autoparts place had a special on a coolant system tester, a mityvac unit specifically designed for bikes and likely snowmobiles, so picked one up and went through the test last evening. The system was pressurized to 15 psi, as the cap is a 1.1 which equates to 15.6 psi, and I observed a very slow pressure drop, over a 2 minute period. The bike runs great, starts easily, so I am somewhat reluctant to tear into it to check for warpage or gasket leaks. I was wondering if it was possible that the internal water pump seal could be the culprit, or is there some other avenue that the coolant could be entering the combution chamber????