1983 Yamaha 30EN Outboards Service Manual, Page 20Get this manual
ADJUSTMENT POWER HEAD Spark plug 1Check electrode condition and wear, insulator color, and electrode gap2Clean the spark plug with spark plug cleaner if necessaryUse wire gauge to adjust the plug gap to specification3If the electrode becomes too worn, replace the spark plug4When installing the plug, always clean the gasket surface, wipe off any grime that might be present on the su rface of the spark plug, and torque the spark plug properlyRemove the cylinder head and install dial gauge to the cyl inder
Standard spark plug: 8-7HS (NGK) Spark plug gap: 0.5 0.6 mm (0.020 0.024 in) Spark plug tightening torque: 20 Nm (2.0 mkg, 14 ft.lb)