The gap between the spark plug electrodes is not the same for all spark plugs and can also be found in the tables of parameters and installation dimensions.
Spark plugs should be cleaned by sandblasting at least every 10,000 km. In this case, the gap between the electrodes is set to the appropriate value. When setting the gap, never bend the middle electrode. because this may cause the porcelain insulator to crack. Before unscrewing the spark plugs, check that there are no foreign objects in the spark plug recesses. A washer, bolt, stone, etc. that gets into the spark plug hole during unscrewing can destroy the valve, valve seat, or cylinder head during the first engine revolutions.
The appearance of the spark plugs can be used to determine the suitability or flawless operation of the spark plugs, the carburetor adjustment, the condition of the combustible mixture and the condition of the engine (pistons, piston rings, etc.). In general it is considered:
| Insulator | brown |
| Electrodes | black or sooty |
| Working condition | spark plugs, carburetor, injection system, engine, etc. are in order |
| Insulator | black or sooty |
| Electrodes | black or sooty |
| Working condition | the mixture is too fat, the distance between the electrodes is too large |
| Insulator | light gray, white |
| Electrodes | gray, small balls of melt |
| Working condition | the mixture is too lean. The spark plugs are poorly sealed or loose. The valves do not close perfectly |
| Insulator | oily |
| Electrodes | oiled |
| Working condition | loose piston, loose piston rings, spark plugs working intermittently |
Since the service life of spark plugs is usually approx. If the spark plugs are 15,000 km, cleaning them every 8,000 km is sufficient. When installing the spark plugs, ensure they are not overtightened, as this will damage the sealing washer. Tightening torque of 15 to 23 kNm must not be exceeded.