What is the role of a motorcycle muffler?
First, let’s review the role of a motorcycle muffler. A muffler is a part that extends rearward from the engine of a motorcycle. Its main role is to expel exhaust gases burned inside the engine and to reduce the exhaust noise that occurs when this happens.
The part that extends from the engine to the rear of the motorcycle is the muffler.
Therefore, if you drive without a muffler, you will end up emitting a lot of exhaust gas and making a loud noise. Also, if there is any abnormality in the muffler, your car may not pass inspection, so it can be said that the muffler is one of the most essential parts for safe driving.
The muffler is made up of three parts
As you can see, the muffler is an essential part of a motorcycle. In the case of a motorcycle, the basic structure of a muffler can be said to be made up of three parts: the “flange” that connects to the engine, the “exhaust pipe” that passes through the exhaust gas generated by the engine, and the “silencer” that connects to the exhaust pipe and reduces exhaust gas and exhaust noise.
Of these, the number of exhaust pipes varies depending on the number of cylinders in the engine, with one for a single cylinder, two for a two cylinder, and four for a four cylinder. In the case of multi-cylinder engines, the exhaust pipes often tend to be combined into a collection section on the way to the silencer.
Exhaust pipe for 4-cylinder engine vehicles
Silencers also vary depending on the number of engine cylinders and the type and characteristics of the bike, and there are various types, such as single-exit on the right side, dual-exit on both sides, and up-type silencers for off-road bikes.
In addition, silencers are extremely important parts not only for motorcycle performance but also for design. Depending on their shape, they can create a variety of images, such as sporty, powerful, or retro, on the side and rear views of the motorcycle.
An example of a single right-side exhaust system for a four-cylinder motorcycle (photo shows a Honda CBR1000RR-R Fireblade SP)
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An example of a single-exit right-side exhaust system for a single-cylinder motorcycle (photo: Honda GB350C)
Example of an up-type muffler (photo: Honda CL250)
An example of a dual exhaust system (photo shows a European-spec Suzuki Hayabusa)
Incidentally, in the case of aftermarket mufflers, there are “full exhaust types” that come as a set with a flange, exhaust pipe, and silencer, and “slip-on types” where you mainly replace only the silencer part. In particular, slip-on types are often called mufflers even though they are just the silencer part. That is how much the silencer is a part that is almost synonymous with the muffler.
Why is it the same as a scarf you wear around your neck?
As you can see, mufflers are important for motorcycles, but as mentioned above, the muffler worn around the neck as cold weather gear is also spelled “muffler” in English.
The English spelling of a scarf worn around the neck to protect against the cold is the same: “muffler.”
The word muffler is derived from the word “muffler,” which means to cover, wrap, or erase. The word is formed by adding the suffix “er,” which means “a person or thing that does something.”
A muffler used as cold weather gear is something that is used to keep the body warm by “covering or wrapping around the neck.” A muffler for a motorcycle or car serves the purpose of “covering or wrapping around the exhaust gases generated by the engine to reduce noise.” In other words, the two words are both performing the same action of “covering or wrapping around,” which explains why they are spelled and pronounced the same.
There are two types of silencers depending on their internal structure.
Incidentally, among mufflers, there are two main types of silencers that reduce exhaust noise by enveloping it, depending on their internal structure.
●Straight structure
●Bulkhead type
A “straight structure” is a type in which the pipes from the inlet to the outlet of the exhaust gas are straight. This type of structure allows the exhaust gas to escape easily, resulting in high performance. The internal pipes are made of metal with many holes, and a material called “glass wool” is wrapped around them to plug the holes, reducing exhaust noise.
On the other hand, the bulkhead type has multiple walls called “bulkheads” inside the silencer. The exhaust sound from the engine bounces off the walls, creating a silencing effect. Compared to the straight structure, the bulkhead type is quieter and does not require maintenance of internal parts such as glass wool. However, since the silencer itself tends to be larger and heavier, it can be said that it is not very suitable for sports bikes.
Bulkhead-type mufflers are often used on scooters.
Important points to note about aftermarket mufflers, which are popular for customization
In addition to genuine mufflers, there are also many aftermarket parts available from aftermarket parts manufacturers, and they are popular as parts for customization and dressing up.
As mentioned above, aftermarket mufflers include the “full exhaust type” which is a set of “flange + exhaust pipe + silencer”, but depending on the car model, there are also “slip-on types” which allow you to mainly change only the silencer part.
There are many full exhaust types that not only look good, but also offer a certain degree of power increase and weight reduction. However, they tend to be expensive, with some types costing over 200,000 yen these days. On the other hand, the appeal of slip-on types is that they can be used to dress up your bike at an affordable price, rather than improving performance.
Example of a full exhaust type aftermarket muffler (photo shows R’s Gear GP Spec single full exhaust muffler for CBR650R)
However, in either case, be aware that if the modifications do not comply with legal noise standards or exhaust gas regulations, they will be considered illegal.
Furthermore, if you are caught riding on a public road with an illegal muffler, you will face severe penalties. First, a maintenance order sticker will be affixed to your motorcycle, and you will be required to take it to a transport bureau or other appropriate authority within 15 days to have it checked to make sure that the muffler complies with the law. If you do not comply, you will be subject to a hefty fine of up to 500,000 yen. Additionally, anyone who makes illegal modifications will be subject to penalties such as imprisonment for up to six months or a fine of up to 300,000 yen.
A poster related to illegal mufflers produced by the Ministry of Land, Infrastructure, Transport and Tourism
To prevent this from happening, when choosing an aftermarket muffler, it’s important to make sure that it complies with regulations and is legal for use on public roads. For example, for motorcycles produced after April 1, 2010, you can only use it on public roads if it’s a government-certified muffler, so be aware of the various rules that apply to aftermarket mufflers. Please be careful not to buy an illegal muffler and attach it to your motorcycle and use it on public roads.
