Honda 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.
When installing a new spark plug, tighten 1/2 turn after the spark
plug seats to compress the washer.
When reinstalling the used spark plug, tighten 1/8-1/4 turn after the
spark plug seats to compress the washer.
TORQUE: 18 N∙m (1.8 kgf∙m, 13 lbf∙ft)
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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