Honda F506 Owner's Manual page 41

3.Visually inspect the spark plug. Discard it if the insulator is cracked or
chipped. Clean the spark plug with a wire brush if it is to be reused.
4.Measure the plug gap with a feeler gauge.
Correct as necessary by bending the side electrode.
The gap should be: 0.7–0.8 mm (0.028–0.031 in)
5.Check that the spark plug washer is in good condition and thread the
spark plug in by hand to prevent cross-threading.
6.After the spark plug is seated, tighten with a spark plug wrench to
compress the washer.
NOTE:
After seating it by hand, tighten a new spark plug 1/2 turn with the
wrench to compress the washer. If you are reusing a plug, it should
only take 1/8–1/4 turn.
CAUTION:
• The spark plug must be securely tightened. An improperly tightened
plug can become very hot and possibly damage the engine.
• Never use a spark plug with an improper heat range.
38
SIDE ELECTRODE
–
0.7 0.8 mm (0.028
SEALING WASHER
–
0.031 in)