1998-2006 Yamaha F20/F25 Outboards Service Manual, Page 85Get this manual
_ 3Measure: Spark plug gap Out of specification
Spark plug gap: 0.9 1.0 mm (0.035 0.039 in)
4Tighten:
Spark plugs Spark plug: 17.2 Nm (1.7 kg, 12.6 ft Ib)
Before installing the spark plug, clean the gasket surface and spark plug surfaceAlso, it is suggested to apply thin film of anti-seize 'compound to the spark plug threads to prevent thread seizure If torque wrench is not available, good estimate of the correct tightening torque is to finger tighten the spark plug and then tighten it another 14 to 12 of turn (6) Always use new spark plug gasket