I have put 15 hours on my supermoto bike (07 YZf450) since putting in a high compression piston and had the head ported. The first few rides it felt great, pulled hard from bottom to top, and I was very happy with the way it ran. Then it started felling a little slower. It was lacking most on top. Today I decided I should check the valves and I find that the intake cam was one tooth retarded! I know it was timed correctly when it was re-assembled, so my question is, is 15 hours too much for one cam chain? I know they yamaha's go through them, but 15 hours!? Now, properly timed, and with a new cam chain it pulls as hard as I remember.