First pay attention to the color of the exhaust gas emitted from the exhaust muffler. If black smoke comes out of the exhaust pipe, you can analyze it and find it in the fuel system and ignition system.
(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 due to of carbon deposition.
Reasons for the fuel mixture to be too rich are usually that the carburetor oil level is too high, the carburetor main air volume hole is clogged, and the carburetor element air filter 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 why the mixture cfuel is too rich.
(2) “Oil leak” from the engine.
When the engine is running, if blue or black smoke is emitted from the exhaust pipe, it indicates that excess engine oil has entered the cylinder, which will cause a large amount carbon deposits on the spark plug. electrode, or can be wetted by engine oil and prevent sparking, this phenomenon is commonly called "engine oil channeling".
For engines, the piston rings on the piston must be checked, especially if the oil seal is worn (the normal side clearance of the piston ring is 0.015~0.045mm, the use limit is 0.12mm). 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 oil seal is hardened or the oil seal lip is excessively worn, the mounting clearance will be too large and the sealing effect will be lost (the standard mounting clearance between the valve and the valve guide is: intake side 0.01? 0.03mm, exhaust side 0.03 ?These two abnormal situations will eventually cause the oil in the valve rocker arm chamber to be drawn into the cylinder along the valve stem during the intake stroke, causing oil combustion. the valve guide, oil seal or valve should be replaced respectively depending on their wear
(3) Check the ignition system
The magneto is demagnetized, the ignition coil (high voltage box) and electronic igniter have internal "false shorts", the generator output terminal and the ignition coil Loose wire connections or "false ground" at the end input, as well as incorrect ignition advance time, or even timing, will affect ignition performance, and poorPoor ignition performance will directly cause carbon deposits on the spark plug electrode.
(4) Pay attention to the model and calorific value of the spark plug;
If the model and calorific value of the spark plug comply with the instructions for use. If the selected calorific value is one or two ratios lower than that specified in the instruction manual, the temperature of the spark plug will rise very high and the heat cannot be dissipated in time, causing abnormal combustion ( i.e. premature ignition), and ultimately causing melting and early damage of the spark plug electrode. 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) Overfilling crankcase oil;
If the crankcase oil is overfilled, the crankcase breather pipe will be blocked, increasing the pressure in the crankcase. , the engine during the gas stroke, it flows into the combustion chamber, burning oil, and thick black smoke comes out of the exhaust pipe.
When the arrow on the 168 gasoline engine spark plug is equipped, the direction of the arrow is up or down. Please answer
If it is a four-stroke motorcycle, the cylinder. has no recovery hole, and the piston and cylinder will form a sealed space, so you don't have to worry about the burner tip falling into the fuel oil tank.
In this case, you can rotate the magneto so that the piston reaches top dead center, then use a magnetic rodto vacuum the burner head. It's just a suggestion, you might as well give it. it's a test.
The arrow on the piston should be facing the front of the engine.
The arrow on the piston should be facing the front of the engine. The piston is marked forward when leaving the factory to avoid being installed backwards. Before installing the piston, the gap between the piston and the cylinder should be measured, placed in the cylinder according to the gap, and matched with the coupling. For couplings with copper sleeves, the piston must be heated and coated with engine oil for installation. the piston pin. Connecting rods without copper sleeves require cold-pressed piston pins. When you press the piston pin, you should clearly see the connection and direction of the piston.