Honda SH300 Owner's Manual page 110

5. Check the new spark plug gap (4) using a
wire-type feeler gauge. If adjustment is
necessary, bend the side electrode (5)
carefully.
The gap should be:
0.80 - 0.90 mm (0.031 - 0.035 in)
Make sure the plug washer is in good
condition.
6. With the plug washer attached, thread the
spark plug in by hand to prevent cross-
threading.
(5)
(4) Spark plug gap
(5) Side electrode
98
7. Tighten the spark plug:
• If the old plug is good:
• If installing a new plug, tighten it twice
NOTICE
(4)
Improperly tightened spark plug can
damage the engine. If a plug is too loose, a
piston may be damaged. If a plug is too
tight, the thread may be damaged.
1/8 turn after it seats.
to prevent loosening:
a) First, tighten the plug:
NGK: 1/2 turn after it seats.
b) Then loosen the plug.
c) Next, tighten the plug again:
1/8 turn after it seats.