2007-2009 Yamaha F15/F20 Outboard Service Manual, Page 121Get this manual
Power unit Shaft holder 5: 90890-06069 8Remove the retaining plate, sprocket, and Woodruff keydrive
5Hold the driven sprocket using the special service tool 4, and then remove the driven sprocket bolt 3
Checking the timing belt and sprocket
S6AG5A60
1Check the interior and exterior of the timing beltReplace if cracked, damaged, or worn2Check the drive sprocket and driven sprocketReplace if cracked, damaged, or worn
NOTE: Make sure that the driven sprocket does not turn when loosening the driven sprocket bolt
Flywheel holder 4: YB-06139 6Remove the driven sprocket and Woodruff key7Install the power unit onto the special service tool as shown, and then remove the drive sprocket nut 6