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: Inspecting Electrodes And Ceramic Insulator
    Courtesy of AMERICAN HONDA MOTOR CO., INC.
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.)

Fig 2: Identifying Electrode Gap
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 below.
Spark Plugs

NGK: IZFR5K-11

DENSO: SKJ16DR-M11

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 18 N.m (1.8 kgf.m, 13 lbf.ft).