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 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
    
    Fig 1: Inspecting Electrodes And 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.
- When using a sand blaster spark plug cleaner, do not clean for more than 20 seconds to avoid damaging the electrode.
Replace the spark plug if the gap is out of specification.
NOTE: Do not adjust the gap (A) of iridium tip plugs

Electrode Gap

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

Fig 2: Identifying Gap Of Iridium 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 as listed.
Spark Plugs

NGK IZFR5K-11

DENSO SKJ16DR-M11

Fig 3: Identifying 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 18 N.m (1.8 kgf.m, 13 lbf.ft).