Spark Plug: Testing and Inspection

Fig. 6 Spark plug inspection:

Check the following points. If a problem is found replace the spark plug Fig. 6.

1. Damaged insulation.
2. Worn electrodes.
3. Carbon deposits: If cleaning is necessary, use a plug cleaner or a wire brush. Clean the upper insulator too.
4. Damaged gasket.
5. Burnt condition of the spark insulator. If it is black with carbon deposits, either misfiring due to improper proportions of gas and air or overheating of the plug may have occurred


Plug gap: 0.75-0.85 mm (0,030-0.034 in).