The use and maintenance methods of motorcycle mufflers

A motorcycle muffler is a device that controls engine exhaust noise, and its function will have a significant impact on the environment. Its function is to allow airflow to pass through normally and reduce radiated noise energy. The exhaust of motorcycle engines has strong airflow pulsation noise. The exhaust port is equipped with a muffler, which can effectively reduce airflow noise, minimize interference with the environment, and increase passenger comfort. But after using the muffler for a period of time, the noise reduction effect will decrease. This article introduces some methods for using, maintaining, and repairing mufflers based on user experience, in order to extend the service life of mufflers.

Motorcycle mufflers can generally be divided into expansion chamber type and impedance composite type. Impedance composite mufflers are mainly used for riding in cars. Light vehicles are composed of shells, sound-absorbing fillers, and sound-absorbing pipes. The exhaust gas enters through the muffler tube in sequence. The second expansion chamber absorbs some noise through expansion and sound-absorbing fillers, and then discharges it into the atmosphere. Impedance composite has good noise reduction effect and high frequency. intermediate frequency. Low frequency attenuation, small size, easy installation. The disadvantage is the removal of carbon deposits. Concrete is relatively difficult, and sound-absorbing materials are prone to failure.

Expansion chamber muffler, also known as resistance muffler, is widely used in bicycles. It is mainly composed of the main cylinder of the muffler, the cylinder center, the muffler, and the partition. The working principle of its noise reduction is similar to that of an electrical filter, which attenuates and reduces some sound waves by changing the acoustic impedance of the sound propagation pipeline. When exhaust gas enters the muffler at high speed, it usually undergoes a three-stage expansion and compression mutation process, greatly reducing the velocity, vibration frequency, and temperature of the airflow, lowering the sound energy, and achieving soundproofing effect. No sound-absorbing material, simple structure, convenient carbon accumulation, good noise reduction effect for mid low frequency airflow pulsation noise, but poor noise reduction effect for high frequency noise. After using the expansion chamber muffler for a period of time, the noise reduction effect is poor, gradually becoming ineffective, and the noise increases. There are two main reasons for muffler malfunction:

One is damage to the partition and cylinder caused by corrosion and impact of engine exhaust gas;

Secondly, due to the condensation of water vapor in the engine exhaust into water in the exhaust pipe, it was not promptly eliminated. Evaporation causes oxidation and rusting of the partition and cylinder. This situation is very evident in areas with high air humidity in the south. At the same time, it is also closely related to the use of vehicles. The impact of short distance use on mufflers when the temperature is low. When the temperature is low and the vehicle is started, the water vapor in the exhaust condenses on the cooler muffler cylinder walls and partitions. If the vehicle is driven for a long time and the temperature of the exhaust pipe increases, the condensed water that cannot be discharged from the drain hole evaporates, which has a small impact on the exhaust pipe; If the vehicle is driven for a short period of time, condensation water that has not been discharged from the exhaust pipe will accumulate, causing corrosion to the cylinder walls and partitions. With the increase of motorcycle usage time, the cylinder and partition will be damaged and perforated.

Therefore, when using a motorcycle, attention should be paid to keeping the drainage hole under the exhaust pipe unobstructed and regularly cleaning it to prevent blockage. Adding some lubricating oil to the exhaust pipe has a certain rust prevention effect. But after driving for a long time, it is necessary to add some lubricating oil. Due to prolonged driving, as the exhaust pipe temperature increases, the original lubricating oil will evaporate. In practical use, drainage holes are prone to blockage and their positions are difficult to clean. At this point, another drainage hole with a diameter of about 2mm can be drilled at an appropriate position under the exhaust pipe to increase drainage capacity, which will also be easier to clear in the future. Due to the small aperture, it will not affect the exhaust and noise of the engine. If the partition of the exhaust pipe is corroded and rotten, the air pipe is intact, and the exhaust noise is loud, here is a simple repair method that can reduce the noise without replacing the entire exhaust pipe. If the trachea is damaged or leaking, it needs to be repaired.

This method is particularly suitable for exhaust pipes used in vehicles such as GS125 and GN125. In theory, since the mid frequency of the jet noise spectrum is inversely proportional to the nozzle diameter, when the diameter of the hole is small enough, the noise frequency can be increased to the ultrasonic range without disturbing people. The specific method is as follows: Find a stainless steel sheet with a thickness of about 0.3mm, and according to the dimensions in Figure 1, dimension A should be as large as possible. For motorcycles with a displacement of 125ml, the total number should be greater than or equal to 140, evenly distributed, and the hole spacing should be greater than or equal to 8mm. While ensuring that the total number of holes remains unchanged, the larger the hole spacing, the better the noise reduction effect. Roll the stainless steel sheet drilled into a large one. A small cylinder with a diameter of approximately 16mm for the large head and 13mm for the small head. The rolled edges have a 5mm wide overlap to ensure maximum tightness and prevent significant air leakage. The small end is formed into a closed shape with pliers, usually squeezed into a star shaped seal shape, with a slight air leakage. This simple muffler is ready.

Insert the small head directly into the hole at the rear of the motorcycle exhaust pipe, and use the elasticity of the stainless steel sheet of the muffler to generate friction with the heart of the exhaust pipe. When fixing the muffler, it should be ensured that the muffler will not fall off due to exhaust impact during driving. The engine exhaust is discharged into the atmosphere through the center of the silencing pipe to achieve the purpose of silencing. A simple muffler tube is made into a platform with a large end and a small end, in order to better distribute the engine exhaust evenly into the center of the tube and reduce resistance. Schematic diagram 2 of the structure and installation of simple mufflers for motorcycles such as GS125 and GN125. www.mopei8.com。

For other types of motorcycle resistant mufflers, this method can also be used for repair. When the motorcycle displacement is greater than 125ml, the number of small holes should be increased. Due to the fact that the partition at the center of the cylinder may not be completely corroded and damaged, when making a simple muffler, the insertion depth of the exhaust port should be checked, and the length dimensions of the non drilled and drilled sections should be adjusted according to the structural dimensions, mainly to ensure that the exhaust hole at the center of the original cylinder overlaps with the drilled section, and all simple mufflers should be inserted into the exhaust port. If size A is reduced, the spacing between the small holes will correspondingly decrease, resulting in poor noise reduction effect. But it cannot reduce the total number of boreholes to prevent engine performance from decreasing due to increased resistance.

Due to a certain margin in the exhaust flow area of the exhaust port, after inserting the stainless steel pipe, the total exhaust port area does not decrease significantly and will not affect the engine power. The resistance generated by exhaust through small holes can be equal to or less than the resistance of the original exhaust pipe itself, and has little impact on engine power and economy. After using for a period of time, it is easy to remove a simple muffler tube for cleaning and inspection. After several months of use, the author did not find any other abnormalities, and the impact on engine efficiency was less than 5%, which meets the requirements of a general muffler. The noise reduction effect can almost reach the level of a new car. When making a simple muffler, two points should be noted: first, to improve the noise reduction effect and increase the spacing between small holes as much as possible; The second is to reduce exhaust resistance and increase the number of small holes as much as possible. This requires the largest possible size A, and when the size A is constant, it should be matched with the spacing and number of small holes. As long as the two work together properly, a satisfactory simple muffler can be made, thereby extending the service life of the entire exhaust pipe.