Spark Plug: Testing and Inspection

INSPECT SPARK PLUG

NOTE:
- Do not use a wire brush for cleaning.
- Do not attempt to adjust the electrode gap of a used spark plug.




a. Check the electrode.
1. Using a megohmmeter, measure the insulation resistance.

Standard insulation resistance: 10 ohms or more

HINT: If a megohmmeter is not available, perform the given simple inspection instead.

b. Alternative inspection method:




1. Quickly accelerate the engine to 4,000 rpm 5 times.
2. Remove the spark plug.
3. Visually check the spark plug.

If the electrode is dry, the spark plug is functioning properly. If the electrode is damp, proceed to the next step.







c. Check for damage to the spark plug threads and insulated area.

NOTE:
- Do not damage the iridium or platinum chip areas.
- If the spark plug is very dirty as a result of combustion, etc., replace it.
- If replacing the spark plug with a new one, do not remove the new spark plug's protective cap until immediately before installing it.
- If the spark plug is dropped, replace it.

If there is any damage, replace the spark plug.




d. Reference:

Maximum electrode gap for a used spark plug: 1.4 mm (0.055 in.)

If the gap is greater than the maximum, replace the spark plug.

Electrode gap for a new spark plug: 1.0 to 1.1 mm (0.039 to 0.043 in.)






NOTE: Never attempt to adjust the gap of a plug.

If the electrode has traces of wet carbon, allow it to dry and then clean with a spark plug cleaner.

Standard air pressure: 588 kPa (6 kgf/sq.cm, 85 psi)

Standard duration: 20 seconds or less

HINT: Only use the spark plug cleaner when the electrode is free of oil. If the electrode has traces of oil, use gasoline to clean off the oil before using the spark plug cleaner.