Failure analysis
1. Blue smoke from the exhaust pipe
The failure phenomenon of blue smoke is: light blue smoke is often seen at the tail of the exhaust muffler during the working process of the engine, and the organic oil is consumed too quickly. The cause of the failure may be: the oil level is too high; the compression pressure of the cylinder is lower than the specified value; the gap between the piston, the piston and the cylinder barrel increases.
2. The exhaust pipe emits black smoke
The fault phenomenon of black smoke is: when the engine is working, the exhaust pipe emits black smoke, and the pungent gasoline smell can be smelled, which is more obvious when accelerating. The cause of the failure may be: the mixture is too thick; the spark plug is not working well; the ignition is too late.
3. White smoke from the exhaust pipe
The original fault phenomenon of white smoke is: when the engine is working, the exhaust pipe emits white smoke. The cause of the failure may be: the fuel contains water; the cylinder or muffler contains water.
Troubleshooting
1. Blue smoke from the exhaust pipe
First check whether the oil level is too high, because the oil level is too high to cause the oil to run up. When checking the oil level, do not check right after the engine has stopped, and check again after stopping for 10 minutes. If the oil level is too high, drain the excess oil in time. If the oil level is normal, check the compression pressure of the cylinder and the wear of the piston, piston ring and cylinder to increase the possibility of the clearance of the engine that has been used for a long time. The increased clearance will cause the oil to run up. After inspection, the cylinder pressure is lower than the specified value, and further inspections should be made to see if the piston is stuck due to carbon deposits, worn out or even lost its elasticity. If the above situation occurs, the piston ring should be cleaned or replaced. When the cylinder barrel is seriously worn and the gap between the piston and the cylinder barrel exceeds the specified value, boring the cylinder, replacing the piston, etc. should be done.
For engines that have just been overhauled or replaced with piston rings, the internal and external cuts (or chamfers) of the piston rings are often installed incorrectly, causing oil to flow up. If the above situation occurs, the piston ring should be reinstalled.
2. The exhaust pipe emits black smoke
Check the concentration of the mixture. After the fault symptoms appear, first check the carburetor damper. When the engine is working normally, is there any phenomenon that the X longitudinal mechanism is stuck or malfunctions and cannot be closed or opened? If so, repair or replace it. Secondly, check: whether the oil level in the float chamber is too high; whether the float leaks and cannot float; whether the main measuring hole needle valve is too open; whether the air filter is blocked, etc. After the engine is turned off, look at the main nozzle from the carburetor. If there is oil flowing out or dripping, it means that the oil level in the float chamber is too high. The tongue of the float should be bent upwards or a proper pad should be added under the needle valve. Film to adjust. Check the float. If there is a crack and oil leakage, it should be repaired or replaced by welding. Note that the weight of the float will increase after welding, and it must be re-adjusted during installation to ensure the normal liquid level. Check whether the triangular needle valve is not tightly sealed, etc., and replace it if any. Check the oil filter, if it is clogged, it should be cleaned or replaced.
Check the spark plug flashover condition. If the spark plug is weak or abnormal, the mixed gas will not burn, and black smoke will appear. Pull out the spark plug and make the sparking normal, and the spark is strong, indicating that the spark plug is not faulty; if the spark of the spark plug is not jumping along the electrode, but sparking around, it means that the sparking of the spark plug is abnormal, and a new spark plug should be replaced; if the spark plug has carbon deposits If it is serious, just clean it.
The engine exhaust is in the process of emitting black smoke. If there are "suds" and "fire" sounds, it means that the ignition is too late. If the above situation occurs, correct it in time.
3. White smoke from the exhaust pipe
The engine exhaust pipe emits white smoke, which is mostly caused by the moisture in the fuel, the cylinder, and the muffler. If white smoke persists, it means that the fuel is unqualified and should be replaced with good quality fuel. If it only emits white smoke during startup and disappears after normal operation, this kind of problem is not a concern.
4. Lack of power
In such cases, the piston ring is aging and the seal is not good, the valve is not tightly closed or the carburetor is blocked! The piston ring should be replaced. Valves and cleaning carburetor.