Honda Outboard Motor BF15A Owner's Manual page 35

6. Thread the plugs in by hand to prevent cross threading.
7. After the spark plugs are seated, tighten with a spark plug wrench to
compress the washers.
NOTE: If installing new spark plugs, tighten l/2 turn after the spark plugs
seat to compress the washers. If reinstalling used spark plugs, tighten
l/8- l/4 turn after the spark plugs seat to compress the washers.
CAUTION:
l
The spark plugs must be securely tightened. Improperly tightened plug
can become very hot and may cause engine damage.
l
Use only the recommended spark plugs or equivalent. Spark plugs
which have an improper heat range may cause engine damage.
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