Exhaust: complete guide for motorcycles and other two-wheelers

February 28, 2019

Central part of the mechanics, the muffler is also the favorite customization accessory of bikers. Here is a guide to choosing the model best suited to your use..

Exhaust: complete guide to motorcycles and other two-wheelers

The different parts of an exhaust

As the name suggests, the muffler, usually placed under the vehicle, allows the escape of the burnt gases. It also serves as a filter to reduce emissions of these polluting gases as well as noise pollution thanks to the silencer. The motorcycle muffler has several elements.

Located at the exit of the cylinders, just under the cylinder head, the manifold and its exhaust valve function to group the cylinders to one or more common outlets. It can be equipped with a catalyst to reduce pollution by finalizing the gas outlet.

On leaving the pot, the exhaust silencer containing the baffle (s) helps cool the gases and reduce their noise. This is the most visible part and the easiest to change. The baffle is a sound attenuator also called in English the DB killer.

The motorcycle muffler: law, sound and pollution

Exhaust systems can improve or degrade engine performance. The pot is an essential technical part.

But it’s also a look, a more or less enticing sound that says a lot about the effect these motorcycles have. Two-wheeler enthusiasts like to personalize their machine by equipping it with a beautiful piece. But be careful, looking for a nice acoustic effect or adding motorcycle parts that throw it away must be done within a legal framework..

Exhaust pipes must be approved and in good condition. If they are pierced, they will no longer be effective. But, legislation mainly focuses on noise, especially in urban areas.

Noise pollution caused by motorized vehicles is one of the main infringements of the highway code on motorcycles. Any noise emission likely to cause discomfort to residents and road users is punished, according to Article R318-3 of the Highway Code, with a fixed fine of € 90, i.e. a 4th class fine.

War is declared on the owners of unapproved mini-motorcycles, pit-bikes, motocross and quads who use them "in the wild". But the law also punishes bikers who modify their motorcycle parts and accessories with for example the removal of the baffle reducing noise.

The text clearly states that "any operation tending to eliminate or reduce the effectiveness of the silencer exhaust system is prohibited". In most cases, checks are done by ear, without using a sound level meter to calculate the decibels.

Why modify the exhaust of your two-wheeler ?

Several reasons push pilots to change pots. Quite simply, if it has been damaged after an accident or a slip. But, most of the time, enthusiasts like install new more designer or lighter parts.

Like the rims on a car, the engine guard or the indicators for the scooter, quad or motorcycle 125cc, the exhaust is the motorcycle equipment that we like to "tuner", because it is true that manufacturers offer mufflers , but too often imposing, with unflattering sounds. The props therefore offer attractive devices, which give a more personal allure to his bike..

But a new pot can also slightly increase the performance of its machine by a few horses..

You should know that you can change only the silencer, or the entire exhaust line. In the latter case, performance can be drastically changed. It will then eventually be necessary to couple it to a suitable air filter or to review the carburetion (carburettors) or the engine mapping for recent motorcycles with injection..

As a reminder, modifying a complete line and therefore increasing the original power of your motorcycle, scooter or other two-wheeler is not allowed. These changes are reserved for off-road motocross or track riding.

How to choose your muffler ?

Before buying a new muffler, it is important to seek professional advice and check that the model is approved. This is all the more true for a second-hand purchase! It will be necessary to look closely if the DB killer has not undergone any modifications.

If you change the pot after a fall, or to boost the sound, it is advisable to turn to a stainless steel exhaust, a standard material offering good value for money, fairly light and robust.

There are also steel pots, but they are still susceptible to corrosion from humidity and high temperature. Carbon can degrade due to heat and vibration; rivets can also take play.

The absorbent material generally ceramic wool or rock wool is then no longer effective and the casing risks burning on contact with hot gases.

Titanium is bound to last over time, but it tends to heat up quickly: be careful not to burn yourself if the pots are located under the saddle.

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