I would like to try the YZ timing on my WR. Should I replace the WR cam with a YZ cam ? Or should I just rotate the cam ? People here are saying that you need to replace the cam. The part catalogue (http://www.yamaha-motor.com/sport/parts/home.aspx) lists the same part number (5TA-12170-00-00) for '03 YZ450 and WR450.