1. The combustible mixture is too rich. The remaining unburned parts will accumulate on the spark plug electrode and be carbonized, causing the spark plug to flash abnormally until it is damaged by carbonization. The reasons for the fuel mixture being too rich are usually that the carburetor oil level is too high, the carburetor main air volume hole is clogged, and the air filter element is seriously clogged. Additionally, the carburetor choke is blocked and cannot be fully opened, or the enrichment valve is not working properly, which is also the reason why the fuel mixture is too rich.
2. Engine oil leak. During engine operation, if blue or black smoke is emitted from the exhaust pipe, this indicates that excess engine oil has entered the cylinder, which will cause the productionfrom a large amount of carbon deposits by the spark plug electrode or its moistening. by engine oil and unable to produce sparks. This phenomenon is commonly referred to as engine oil channeling. For two-stroke engines, check whether the oil volume of the oil pump is too large and whether the rod sleeve seal and check valve are defective. For four-stroke engines, check the piston rings on the piston, especially the oil ring, whether it is worn or not. Then remove the intake valve and check for carbon and wet grease deposits on its head and back. If the valve and valve guide are severely worn, the valve guide seal is hardened, or the seal lip is excessively worn, the mounting gap will be too large and the effect of The seal will be lost. Both of these abnormal situations will eventually cause oil to be sucked intothe valve rocker arm chamber into the cylinder along the valve stem during intake air summing, causing oil combustion. In this regard, the valve guide, oil seal or valve must be replaced respectively depending on their wear.
3. In the ignition system, the magneto is demagnetized, the wire connections inside the ignition coil and the electronic ignition, the generator output end and the coil input end are demagnetized. The ignition is loose and the ignition timing is incorrect. If it is not properly timed, it will affect the ignition performance, and poor ignition performance will directly cause carbon deposits.
4. Pay attention that the spark plug model and calorific value comply with the instructions for use. If the selected calorific value is one or two ratios lower than specifiedin the instruction manual, the heat cannot be dissipated in time, causing abnormal combustion and possibly melting the spark plug electrode and causing premature damage. When the spark plug itself is installed and used, some defects are not easy to detect and also affect the ignition performance. For example, if the spark plug is poorly sealed, if the spark plug is not firmly fixed, if the spark plug insulation is cracked, etc., it should be adjusted or replaced in time . 5. If the crankcase oil is overfilled and the breather pipe is blocked, the pressure in the crankcase will increase and the crankcase will not be balanced.