Honda HHB25 Owner's Manual page 46

4. Measure the plug gap with a feeler gauge.
The gap should be 0.6 – 0.7 mm (0.024 – 0.028 in). Correct as
necessary by carefully bending the side electrode.
0.6 - 0.7 mm
(0.024 - 0.028 in)
5. Check that the sealing washer is in good condition and thread the
spark plug in by hand to prevent cross-threading.
6. After the spark plug is seated, tighten with a spark plug wrench to
compress the washer.
NOTE:
After a new spark plug has been seated by hand, it should be
tightened 1/2 turn with a wrench to compress its washer.
If a used plug is being installed, it should only require 1/8 to 1/4 turn
after being seated.
CAUTION: The spark plug must be securely tightened. An improperly
tightened plug can become very hot and possibly damage the engine.
7. Attach the spark plug cap.
8. Put the spark plug maintenance cover back.
SIDE ELECTRODE
SEALING WASHER
43