1. Five reasons causing engine failure

1. Wear and tear during startup

Firstly, the stage of the most significant wear and tear for the engine occurs during startup. Some people, regardless of the season, do not develop the habit of warming up the engine before driving. In fact, this is very harmful to the vehicle because during startup, the oil pump needs some time to push the oil to the cylinder head and other parts. This period of direct operation causes significant wear and tear. Additionally, during cold starts, lubrication is poor and the wear is also very significant. The correct operation is to start the vehicle when the water temperature rises above 70 degrees. For vehicles without a water temperature gauge, with electronic fuel injection systems, one can wait until the idle speed drops to the normal range before starting. For carbureted vehicles, they need to idle for a while. 

2. Skipping Down and Skipping Up Gears

The normal practice is to descend and ascend gears step by step. One should start from the first gear and descend gears gradually as the speed decreases. Some incorrect practices involve starting in 2-3 gears. This is very harmful to the clutch plate as it can easily cause the clutch to overwork and wear out. If this situation persists for a long time, it can even burn out the clutch plate. Skipping down gears mainly tests one's perception of speed and gear positions. Each gear has a corresponding speed range. If this is not mastered properly, it could result in minor issues such as incorrect gear shifting, damaging the fork and gear wheel. In severe cases, the engine casing may crack, the gear teeth may be damaged, the fork or fork shaft may become bent, and the rear wheel may burst. 

3   Oil issues and engine sludge

The most important step in vehicle maintenance is the oil. If the oil is of poor quality or not suitable, or if it is fake, over time it can cause cylinder seizure and engine failure. The main reasons for cylinder seizure and engine failure are only two: either the oil is lacking or completely absent, or the oil pump fails and the oil passage of the oil filter is blocked. These two reasons are mostly caused by not changing the oil regularly, resulting in thermal evaporation loss of the oil, forming sludge that blocks the oil passage and the filter, leading to insufficient oil supply or insufficient oil pressure, and ultimately causing cylinder seizure and engine failure. Additionally, fake oil can also produce a lot of sludge. Generally, we can observe whether there is excessive sludge by the color of the oil window. For those without an oil window, we can check the adhering substances on the oil dipstick. It is best not to wait until the oil is too black before changing it. Also, we can use kerosene or diesel and engine cleaning oil to clean the engine.

4   Gasoline issues

The higher the compression ratio, the higher the gasoline grade. However, a higher gasoline grade does not necessarily mean it is better. Some small oil refineries in China like to pass off inferior products as good ones. Therefore, it is best to go to large gas stations for refueling. To return to the main topic, gasoline grades are generally either high or low. That is to say, a car with a low compression ratio can generally be refueled with a high-grade gasoline, but a car with a high compression ratio should not be refueled with a low-grade gasoline. For example, if the cylinder vibrates severely, there will be a lot of noise, and in severe cases, the valve may break and leak the cylinder, and the spark plug may frequently fail. Generally, as long as you feel that the car has backfire and continuous belching, it is mostly related to the gasoline (if the oil circuit system of the vehicle is normal).

5   Engine carbon deposits

Having carbon deposits in the engine is normal and an inevitable phenomenon. However, there is a limit to it. Beyond that limit, there will be problems.

Generally, there are two reasons for excessive carbon deposits: one is poor gasoline quality and incomplete combustion, and the second is not warming up the engine frequently, short-distance driving and low-speed driving.

Carbon deposits mainly affect two aspects of the vehicle: one is increased vibration, and the other is unstable idle. The main impact of carbon deposits is on the piston top, valve base, spark plug and fuel injector.

If there is excessive carbon deposit on the piston top, it will first cause increased vibration, then as it spreads to the piston ring groove, it will eventually lead to the piston ring seizing and losing cylinder pressure or reduced cylinder pressure.

Light carbon deposits on the valve cause poor valve sealing, making it difficult to start and idle. Severe cases can lead to reduced valve return speed, piston top valve, and excessive carbon deposits on the fuel injector, resulting in poor atomization, black smoke and unstable idle. Indirectly or directly, it can cause the spark plug to fail. The main way to avoid excessive carbon deposits is to develop the habit of warming up the engine, not using poor-quality gasoline, and driving more frequently on short distances and less frequently on high-speeds.

II. Causes of carbon deposits

During the daily use of motorcycles, the formation and cleaning of carbon deposits are things that many motorcycle owners do not understand at all. The formation and accumulation of carbon deposits are closely related to the oil type, riding habits, and maintenance cycle. For example, if motorcycles are constantly using inferior oil, frequently riding short distances (that is, riding no more than 10 kilometers each day and each ride not exceeding 5 minutes), and not replacing the air filter regularly, it is easy to cause an increase in carbon deposits in motorcycles. However, motorcycle owners generally do not know this until the vehicle cannot start or is taken to the repair station, and then they will be informed by the repair worker. So under what circumstances should we clean the carbon deposits?

The direct consequence of carbon deposits on the spark plug

1. Difficulty starting cold engines ◦ This is the most common initial symptom. Carbon deposits cover the electrodes and insulators of the spark plug, which is equivalent to connecting a resistor in parallel between the electrodes, causing a portion of the ignition energy to be "leaked", resulting in a weakened spark from the spark plug, or even no spark at all. This is particularly obvious in cold engines, and you may hear the starter turning but the engine does not ignite. 2. Unstable idling and prone to stalling  ◦ When the engine is at low speed (idle), it requires stable and powerful sparks to maintain operation. If the spark plugs intermittently fail to ignite due to carbon deposits, it will cause the engine speed to fluctuate, the vehicle to shake, and even sudden stalling.

3. Weak acceleration and reduced power  ◦ This is a direct manifestation of "loss of power". When you step on the accelerator, the engine needs a denser and more intense ignition to burn more mixture. If the spark plugs fail to ignite effectively due to carbon deposits at this time, it will cause the mixture in that cylinder to fail to burn fully or not burn at all. This will directly lead to a decrease in engine power output, and you will feel that the car is "choked", "can't pick up speed", "has pauses", that is, it loses its normal power.

4. Increased fuel consumption

Due to insufficient combustion, the fuel is not effectively converted into power but is wasted or forms more carbon deposits, resulting in a significant increase in fuel consumption.

5. Exceeding emission standards and unpleasant exhaust smell

Incomplete combustion produces a large amount of carbon monoxide (CO) and hydrocarbons (HC), causing a pungent exhaust smell and failing to pass environmental protection tests. When you slam on the accelerator, you can almost see black carbon particles spewing from the exhaust pipe.

6. Severe cases may damage other components

Long-term poor combustion causes unburned gasoline to flow into the exhaust pipe, which may continue to burn inside the exhaust pipe or the three-way catalytic converter, leading to the high-temperature damage of these components. At the same time, gasoline will dilute the engine oil, reducing its lubrication performance, and exacerbating engine wear.

All of these phenomena may be caused by an increase in engine carbon deposits. Many people may consider carbon deposits as a normal phenomenon and think there is no need to deal with it. However, excessive carbon deposits not only affect fuel consumption but also may damage the valves, cylinder head valve seats, or cause piston ring and oil ring sticking, which can lead to engine oil burning. This oil burning is difficult to detect easily and will not be discovered until it is not maintained in time, resulting in cylinder scoring.

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