Honda Power Products TILLER FJ500 Manuel De L'utilisateur page 50

4.Check that the spark plug washer is in good condition and thread the
spark plug in by hand to prevent cross-threading.
SPARK PLUG WRENCH
5.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.
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