Motorcycle Engine Cylinder Life Depends On These Details

Motorcycle Engine Cylinder Life Depends On These Details

Date:Oct 04, 2019

As we all know, the service life of motorcycles is calculated by the overhaul mileage of motorcycles. The most important sign of overhaul mileage is the wear of the cylinder bore and the wear of the crankshaft. The wear of the bore is the most important. When the cylinder bore is worn, the gap between the piston and the inner wall of the cylinder increases, causing a knocking sound between the piston and the inner wall of the cylinder and leaking air. At this time, the fuel consumption of the motorcycle increased sharply, the sewage discharge increased greatly, the mechanical efficiency and power drastically decreased, and overhaul was necessary. The main project of the overhaul is to smash the cylinder and change the piston to restore the normal clearance between the piston and the inner wall of the cylinder. The clearance of the domestic motorcycle is generally 0.03 ~ 0.06mm (refer to the gap between the piston skirt and the cylinder), and the clearance of the foreign high-performance engine can be as small as 0.015 ~ 0.025mm. It can be seen that the wear of the cylinder bore directly determines the service life and overhaul period of the motorcycle.

Car owners want their motorcycles to last as long as possible. The overhaul mileage of genuine domestic motorcycles is generally 50,000 to 100,000 km, and the performance of foreign high-performance motorcycles is 100,000 to 150,000 km. The use of reasonable upper limit, the use of unreasonable lower limit may not be achieved; fake and shoddy motorcycles may run 10,000km, and some can only maintain the 6000km warranty period, once the warranty period is exceeded, the owner has to pay for overhaul or replacement New cylinders cause undue economic losses. Needless to say, how to extend the service life of the cylinder is of great practical significance, and it is related to the vital interests of each owner. Therefore, it is necessary to introduce some corresponding measures to avoid the wear of the cylinder diameter and prolong its service life.

First, the purchase of brand-name or genuine car is the key

One of the main reasons for the high-performance engine's service life of up to 100,000 to 150,000 km is the plating of a layer of high-performance ceramic composite material on the inner wall of the cylinder. In recent years, China Everest Corporation and Chongqing Huawei Company have also begun to apply new technologies for cylinder ceramic coating. For example, Chongqing Huawei's “Golden Pottery Technology” uses chemical vapor deposition technology to deposit a layer of Ni-SiC composite ceramic film on the inner wall of the cylinder. The ceramic particles infiltrated into the inner wall of the cylinder are only 0.3μm in diameter, compact in structure and high in surface roughness. The coefficient of friction is only 0.06 to 0.082. The coating has the comprehensive properties of high temperature resistance, corrosion resistance, self-lubrication, high strength and high wear resistance. After testing, the wear of the cylinder in 200000km is less than 0.10mm, and the clearance of the cylinder can be reduced to 0.015~0.025mm, without worrying about the expansion cylinder, the pulling cylinder and the air leakage, reaching the international advanced level. It is ideal for motorcycle enthusiasts to purchase a car with this type of cylinder.

Second, the new car has to go through a good run-in

When the motorcycle is shipped from the factory, the factory requires the user to carry out the new car running-in, and the running-in period is generally between 1500 and 2500km. In order to ensure the quality of the running-in, some factories add a limited speed tube at the motorcycle carburetor hose, so that the speed of the new car is lower than the speed of the normal use. During the running-in period, the user must not arbitrarily remove the speed limit tube; it is strictly forbidden to drive at high speed with low speed or low speed; it is best not to carry people without load; avoid driving on the bad road with unevenness as much as possible to avoid bearing Larger load. For two-stroke motorcycles that use mixed oil, the mixing ratio of gasoline to lubricating oil should be increased to about 20:1 to make it easier for the cylinder surface to run in.

Third, the cylinder surface should have good lubrication

The piston speed of modern motorcycle engines is so high that even if the lubrication is lost in a short period of time, it may cause severe wear and even damage on the inner surface of the cylinder. In order to avoid dry friction, it is important to ensure that the engine is in good lubrication when it is running. On the one hand, always check the oil pressure and oil scale to avoid using the motorcycle in the absence of lubricating oil; on the other hand, pay attention to the proper viscosity of the lubricating oil, so that it can adhere well to the cylinder and piston surface. In order to form a liquid friction.

Fourth, the air entering the cylinder should be cleaned

The air entering the cylinder from the air filter, if it contains a lot of dust or tiny sand, will quickly increase the wear on the inner surface of the cylinder like the abrasive, so the air entering the cylinder must be very clean. On the one hand, it is necessary to remove the dust in the air filter regularly (about 1000km) and replace the filter element if necessary; on the other hand, always check the sealing of the joints of the air filter to prevent the dirty air from entering the cylinder without passing through the filter. In order to improve the filtration effect, a thin foam sponge can be added to the outer core of the filter, and the foam sponge must be washed once a day to avoid clogging. With high temperature resistance, corrosion resistance, self-lubricating, high strength, high wear resistance and other comprehensive properties. After testing, the wear of the cylinder in 200000km is less than 0.10mm, and the clearance of the cylinder can be reduced to 0.015~0.025mm, without worrying about the expansion cylinder, the pulling cylinder and the air leakage, reaching the international advanced level. It is ideal for motorcycle enthusiasts to purchase a car with this type of cylinder.

Fifth, avoid the phenomenon of sticking cylinder

Sticking cylinder phenomenon is the block-like adhesion between the piston and the cylinder surface, which will cause the cylinder and piston to be scrapped, causing significant economic losses. The main reason for the production of the sticking cylinder is that the engine is overheated, which causes the lubricating oil to lose its lubricating effect. The so-called overheating means that the engine temperature exceeds the normal use temperature. After the power switch is turned off, the engine continues to operate through self-ignition, and the oil on the cylinder head and cylinder block surface is scorched and smoked. Generally, the surface temperature of the cylinder fins does not exceed 180 ° C. The temperature of the lubricating oil in the crankcase of the four-stroke machine does not exceed 95 ° C. It can be measured by a surface thermometer. The spark plug can also be removed to observe the color of the spark plug skirt. The spark plug works normally in dark red or Brown, if there is a metal bead on the spark plug skirt, it means severe overheating; you can also use the method of spit water to check if the saliva sounds "sweet" on the heat sink, it means the temperature is very high, you must stop and cool down in time. Wait until the temperature drops and continue driving.

1. Ensure that the engine has good heat dissipation

First, observe whether the cylinder and cylinder head fins are muddy and oily. If so, use a fine brush, soapy water or a special metal cleaner to gently clean it, then rinse it off with clean water. For forced air-cooled engines, check whether the fan is good, whether there is any breakage, whether the cooling air duct is natural and smooth, and whether the air hood has air leakage; for water-cooled or oil-cooled engines, always check whether the coolant or cooling water leaks. Insufficient, whether the pump or oil pump works normally, whether the water channel is blocked or not. If there is a fault, it should be repaired or replaced in time to prevent the engine from being poorly cooled and overheating.

2. Ensure good ignition performance

Exceeding the lead or lag, in addition to causing the engine to overheat, but also directly aggravate the wear on the surface of the cylinder. When the ignition time is ahead, when the piston has not completed the compression process, that is, the compression process is still in progress, the spark plug has already emitted an electric spark to ignite the mixture, forcing the piston to slow down sharply, and the piston is knocked by the undying impact force. Strike the cylinder to aggravate the wear of the inner surface of the cylinder; when the piston reaches the top dead center, it should require a strong explosive force to push the piston down to do work, but most of the combustible mixture has burned during the compression process, not only causing serious power loss, but also burning Exhaust gas cannot be discharged in time, causing the engine to overheat. The ignition time is too late, that is, the piston has left the top dead center a lot, even when it is close to the bottom dead center, it will ignite and explode. Most of the fuel will not run until it burns to the exhaust pipe, and the malignant combustion in the exhaust pipe is not only Serious loss of power will also cause the engine to overheat; more seriously, because the piston can not continue to move down at the bottom dead center, the combustible gas will suddenly produce a very strong impact, which strongly impacts the piston. Knocking on the cylinder greatly increases the wear of the cylinder.

The above-mentioned fault is judged by: when the ignition is ahead, the engine is difficult to start, and the foot is started with strong repulsive force. After starting, the operation is not smooth, and the throttle engine is knocked. When the ignition is delayed, the muffler is fired at the start, and the throttle is enlarged. The operation is weak, the speed is not high, the sound is dull, and after a high speed operation for a period of time, the engine leaks oil, the bearing is loose, and the noise increases. Repairs should be made in time after the above conditions occur. Generally, there are contact igniters and ordinary capacitor discharge type CDI igniters, and since the ignition advance angle is basically fixed, it cannot be automatically advanced in advance with an increase in engine speed, and thus the above-mentioned failure is liable to occur. Whenever possible, use an analog ACDI electronic igniter or digital full-transistor igniter with automatic advance angle.

3. Ensure that the carburetor works well. Excessive or excessive concentration of the carburetor can also cause the engine to overheat. If it is too thin, the burning rate will decrease, the burning time will be prolonged, and the cylinder temperature will rise. If it is too rich, the combustion will be insufficient, and carbon deposit will easily occur. If the piston top and the combustion chamber have too much carbon, the combustion chamber volume will become smaller and the compression ratio will be smaller. Increase, easy to produce knock and overheat; if the exhaust port carbon deposit too much, so that the exhaust is not smooth, but also make the engine overheat; excessive carbon deposition will seriously affect the engine's heat dissipation performance, resulting in engine overheating, and easy to produce Local high hot spot and spontaneous combustion, causing the normal ignition of the combustible gas flame to collide with the high-hot spot spontaneously ignited flame wave, forming a powerful explosion impact force in the cylinder, ie, knocking, causing the piston to violently strike the cylinder and accelerate the inner surface of the cylinder The wear and tear, especially the strong detonation for a long time, tends to make the piston and the surface of the cylinder surface high and the hot metal is soft and melted to produce a sticking cylinder phenomenon; when there is more carbon in the piston top and the cylinder head, the carbon deposit will fall into The cylinder body causes scratches and abrasions on the surface of the cylinder. Therefore, it is important to properly adjust the mixing ratio of the carburetor and periodically remove carbon deposits.

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