Inspection and Repair: Notes

The spark plug affects entire engine performance and therefore its inspection is very important.

• Check electrode and insulator for presence of cracks, and replace if any.
• Check electrode for wear, and replace if necessary.
• Check gasket for damage, and replace if necessary.
• Measure insulation resistance with an ohmmeter, and replace if faulty.
• Adjust spark plug gap to 1.05 mm (0.04 in).

• Check fuel and electrical systems if spark plug is extremely dirty.
• Use spark plugs having low heat value (hot type plug) if fuel and electrical systems are normal.
• Use spark plugs having high heat value (cold type plug) if insulator and electrode are extremely burned.