Spark Plug Inspection

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 plug 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
    
    Fig 1: Identifying Electrodes & Ceramic Insulator
    Courtesy of AMERICAN HONDA MOTOR CO., INC.
If the spark plug electrode is dirty or contaminated, clean the electrode with a plug cleaner.
NOTE:
- 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.
Do not adjust the gap of platinum tip plugs (A); 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.)

Fig 2: Identifying Gap Of Platinum Tip Plugs
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Replace the plug at the specified interval, or if the center electrode is rounded (A). Use only the spark plugs listed.
Spark Plugs:

NGK: PFR7G-11S

DENSO: PK22PR-L11S

Fig 3: Identifying Rounded Center Electrode
Courtesy of AMERICAN HONDA MOTOR CO., INC.
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 25 N.m (2.5 kgf.m, 18 lbf.ft).