Honda CBR125RW - Owner's Manual > Spark Plug

Spark Plugs Recommendation

Use only the recommended type of spark plugs in the recommended heat range.

Using spark plugs with an improper heat range can cause engine damage.

Spark Plug Inspection & Replacement

1. Clean any dirt from around the spark plug base.

2. Disconnect the spark plug cap (1).

Take care to avoid damaging the spark plug wire when disconnecting the cap.

3. Using a spark plug wrench (2), remove the spark plug.

RIGHT SIDE

1. spark plug cap
2. spark plug wrench

4. Inspect the electrodes and center porcelain for deposits, corrosion, or carbon fouling. If the corrosion or deposits are heavy, replace the plug.

Clean a carbon or wet-fouled plug with a plug cleaner, if available, or a wire brush.

5. Check the spark plug gap (3) of each new plug, using a wire-type feeler gauge. If adjustment is necessary, bend the side electrode (4) carefully.

The gap should be: 0.70-0.80 mm (0.028-0.031 in)

3. spark plug gap
4. side electrode

6. With the plug washer attached, thread the spark plug in by hand to prevent cross-threading.

7. Tighten each 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:

1. First, tighten the plug:
   NGK: 1/2 turn after it seats.
   DENSO: 3/4 turn after it seats.
2. Then loosen the plug.
3. 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.

See also: