Honda CRF125F 2023 Owner's Manual page 87

Spark Plug
1. Clean any dirt from around the spark plug
base.
2. Disconnect the spark plug cap.
3. Remove the spark plug with a plug wrench.
4. Inspect the spark plug electrodes for wear.
The center electrode (1) should have square
edges. The side electrode (2) should not be
eroded. The insulator should not be cracked
or chipped.
5. Check the spark plug gap (3), using a wire-
type feeler gauge. If adjustment is necessary,
bend the side electrode carefully. The gap
should be:
0.031- 0.035 in (0.80 - 0.90 mm)
Make sure the plug washer is in good
condition.
If you have to install a new plug, first check
the gap.
6. With the plug washer attached, thread the
spark plug in by hand (to prevent cross-
threading).
78
Servicing Your Honda
7. Tighten the spark plug:
• If the old plug is good:
1/8 turn after it seats.
• If installing a new plug, tighten it twice to
prevent loosening:
a) First, tighten the plug:
1/2 turn after it seats.
b)Then, loosen the plug.
c)Next, tighten the plug again:
1/8 turn after it seats.
An 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 threads may be damaged.
8. Reinstall the spark plug cap. Take care to
avoid pinching any cables or wires.