2007-2009 Yamaha F15/F20 Outboard Service Manual, Page 59Get this manual
CHK ADJ CAUTION:
Periodic check and adjustment
Checking the timing belt
NOTE: Perform steps 24 for each spark plug3Check the spark plugReplace if the electrodes are eroded or there is excessive carbon or other deposits, or if the gasket is damaged4Check the spark plug gap aAdjust the spark plug gap if out of specification
Do not turn the flywheel magnet counterclockwise, otherwise the water pump impeller may be damaged1Remove the sprocket cover and manual starter(Manual starter model) Remove the sprocket cover and flywheel magnet cover(Electric starter model) 2While turning the flywheel magnet clockwise, check the interior and the exterior of the timing beltReplace the timing belt if cracked, damaged, or wornSpecified spark plug: DPR6EB-9 (NGK) Spark plug gap a: 0.80.9 mm (0.0310.035 in) 5Install the spark plugs, tighten them temporarily, and then tighten them to the specified torque using spark plug wrenchSpark plug: 17 Nm (1.7 kgfm, 12.5 ftlb)