Well I've got 23 hrs. on my 07 yzf450. I just finished my winter maintainance and went to check the valve clearance. This is my first four stroke and have never done this before. I did buy a good tapered feeler gauge to use. The intakes checked out. When checking the exhaust I did the outside one first and found it to be in spec but I had a hell of a tme getting the feller gauge in the middle one. At first I thought the vave was tighter than the other one until I really arced the feeler gauge as I slid it in. In that particular spot on the head, behind that valve, there seems to be a part of the casting that gets in the way and requires a sharp angle to be put on the feeler guage thus creating the illusion of more drag and friction than what's actually there. After fighting with it for a bit, it checked out as well. Just wondering if anyone else has had the same difficulty.