Spark Plug Inspection

1.Inspect the electrodes and ceramic insulator.

  • Burned or worn electrodes may be caused by:
    • Advanced ignition timing
    • Loose spark plug
    • Plug heat range too hot
    • Insufficient cooling

  • Fouled plugs may be caused by:
    • Retarded ignition timing
    • Oil in combustion chamber
    • Incorrect spark plug gap
    • Plug heat range too cold
    • Excessive idling/low speed running
    • Clogged air cleaner element
    • Deteriorated ignition coils


2.If the spark plug electrode is dirty or contaminated, clean the electrode with a plug cleaner.

  • Do not use a wire brush or scrape the iridium electrode since this will damage the electrode.
  • Use a chemical cleaner such as Carb Spray to clean contamination on the electrode.
  • When using a sand blaster spark plug cleaner, do not clean for more than 20 seconds to avoid damaging the electrode.

3.Do not adjust the gap (A) of iridium tip plugs; replace the spark plug if the gap is out of specification.

Electrode Gap 
Standard (New): 1.0-1.1 mm (0.039-0.043 in.) 


4.Replace the plug at the specified interval or if the center electrode is rounded (A). Use only the listed spark plugs.

Spark Plugs 


5.Apply a small amount of anti-seize compound to the plug threads, and screw the plugs into the cylinder head, finger-tight. Then torque them to 18 N·m (1.8 kgf·m, 13 lbf·ft).