71cc Wood Cutting Chain Saw 372XT 372 Chainsaw

When the gasoline engine of the chainsaw is working, gasoline burns inside the cylinder and exhaust gases are discharged from the engine through the exhaust pipe. Normal exhaust gas is invisible to the naked eye. When the fuel is not completely burned or the engine is not working properly, there will be hydrocarbons, carbon monoxide, nitrogen oxides, and carbon particles in the exhaust gas, and the exhaust gas will appear abnormally white, black, or blue. We can judge the combustion of gasoline based on the color of the engine exhaust and take corresponding troubleshooting measures.

When a gasoline engine is operating, gasoline burns inside the cylinder and exhaust gases are discharged from the engine through the exhaust pipe. The exhaust gas mainly contains water vapor, carbon dioxide, and nitrogen. Normal exhaust gas is invisible to the naked eye.

When the fuel is not completely burned or the engine is not working properly, there will be hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and carbon particles in the exhaust gas, and the exhaust gas will appear abnormally white, black, or blue. We can judge the combustion of gasoline based on the color of the engine exhaust and take corresponding troubleshooting measures.

1、 Emitting white smoke

The white smoke in the exhaust is mainly composed of fuel particles or water vapor that have not been fully atomized and burned. Therefore, any situation that causes the fuel to not be fully atomized or water to enter the cylinder will cause the exhaust to emit white smoke.

The main reasons for white smoke emitted by chainsaw gasoline engines are as follows:

1. The temperature is low and the cylinder pressure is insufficient, resulting in poor fuel atomization, especially during the initial cold start when white smoke is emitted from the exhaust;

2. Muffler inlet water;

3. High water content in fuel, etc.

When the chainsaw starts cold, the exhaust emits white smoke. If the white smoke disappears after the engine warms up, it should be considered normal. If the chainsaw engine still emits white smoke during normal operation, it is a fault. The fault should be eliminated by cleaning the water in the muffler, replacing fuel, and other methods.

2、 Emitting blue smoke

The blue smoke in the exhaust is mainly the result of excessive oil entering the combustion chamber and participating in combustion. Therefore, any cause that causes oil to enter the combustion chamber will cause blue smoke from the exhaust.

The main reasons for blue smoke emitted by chainsaw engines are as follows:

1. Wear of piston rings, breakage of piston rings, and rotation of piston ring openings together;

2. Improper assembly or aging failure of valve oil seals, loss of sealing function;

3. Valve guide wear;

4. Severe wear of pistons and cylinder walls;

5. Engine side mounted or inverted;

6. Respirator blockage;

7. The oil grade is incorrect;

8. Excessive amount of oil added.

If there is a blue smoke malfunction in the engine, the first thing to check is whether the oil in the chainsaw is overfilled. Next, it is generally necessary to disassemble and inspect the machine to identify the cause and determine a solution to eliminate the problem.

3、 Emitting black smoke

If the exhaust pipe of the chainsaw emits black smoke, it is because gasoline has not been fully burned and the engine exhaust contains black carbon particles.

The full combustion of gasoline requires a specific ratio of gasoline and air to be maintained in the combustion chamber. If the air ratio in the combustion chamber is too low or too high, it can cause the engine to emit black smoke. So, the main reasons why small chainsaw gasoline engines emit black smoke are as follows:

1. The main nozzle of the carburetor is worn out;

2. The air filter is dampened or blocked by a large amount of dust, resulting in excessive intake resistance and insufficient intake volume;

3. Engine overload operation;

4. The main nozzle of the carburetor is selected incorrectly. For example, when the engine is used in high-altitude areas, due to the decrease in oxygen content in the atmosphere, a specialized main nozzle for high-altitude should be selected, otherwise it may lead to black smoke.

For gasoline engines emitting black smoke, inspection and troubleshooting can be carried out by replacing the air filter, replacing the main nozzle, and confirming whether the engine is overloaded.