Honda EB3500X Owner's Manual page 28

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 com-
press the washer.
NOTE: If installing a new spark plug, tighten l/2 turn after the spark plug
seats to compress the washer. If reinstalling a used spark plug, tighten
l/8- l/4 turn after the spark plug seats to compress the washer.
CAUTION: The spark plug must be securely tightened. An improperly
tightened spark plug can become very hot and may damage the engine.
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