Honda F660 Manuel De L'utilisateur page 40

2. 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.
3. Measure the plug gap with a feeler gauge.
Correct as necessary by bending the side electrode.
The gap should be:
4. Check that the spark plug washer is in good condition and thread the
spark plug in by hand to prevent cross-threading.
5. After the spark plug is seated, tighten with a spark plug wrench to
compress the washer.
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. −
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.
0.7 0.8 mm (0.028 0.031 in) − −
0.7 0.8 mm −
(0.028 0.031 in) −
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