How Does a Motorcycle Baffle Work?


How much attention do you pay to your motorcycle’s exhaust? And what about the baffle?

Motorcycle exhausts usually come with the baffles installed, and they are almost a must-have, but why is that?

Many riders will have different questions about motorcycle baffles—especially when it comes to how exactly they work and affect the motorcycle.

How does a motorcycle baffle work? A motorcycle baffle is a metal tube that makes motorcycles quieter and, at the same time, creates a low level of back pressure that is needed for the motorcycle engine to work properly. Motorcycle baffles work by creating diversions and alternative routes for the exhaust gas to travel through.

Motorcycle baffles seem like a very simple thing, but there are a few interesting details about them that every rider should be aware of. Below I go into more detail about baffles and how they work.

A zoom in on a motorcycle exhaust pipe with a baffle installed

What is a motorcycle baffle?

Motorcycle baffles are relatively easy to manufacture as they are a simple item.

Motorcycle baffles are a metal tube that is inserted inside the exhaust pipe. They are usually made from metal that has been perforated. The size of the perforations and their design can vary drastically and will affect the effectivity of the baffle.

Many exhaust pipes will come with a standard baffle already installed. However, some aftermarket exhaust pipes do not come with a baffle. Baffles come in a variety of different designs, diameters, and lengths. 

Aftermarket motorcycle baffles are also available. 

The design of the baffle is important as this is what affects its performance and sound-reducing capabilities. 

Normally we have a few different types of motorcycle baffles.

There can also be some variance in their design; some baffles are hollow, and others have an end cap inside.

Hollow or straight through baffles are the most basic type of motorcycle baffle. Those baffles will create small amounts of backpressure and allow the motorcycle to have a nearly baffle-less sound.

However, some baffles are not hollow and will have an end cap (or a blocker) that will serve as a stop for the exhaust gas coming down the exhaust pipe. The cap will slow down the exhaust gas significantly. After hitting the baffle’s cap, the exhaust gas will then be directed up and around the cap and through the holes. Baffles that come with a blocker design are a lot quieter.

Wrapped baffles are designed to keep the motorcycle as quiet as possible; they will provide even more sound dampening capabilities. These motorcycle baffles are usually wrapped with fiberglass sheathing.

Motorcycle baffles that have been designed especially for lowering the sound can be between 3 to 10 decibels quieter than straight hollow baffles.

Some baffles can have several different chambers through which the exhaust gas is directed. Those extra diversions of the exhaust gas will also slow down the speed of the exhaust gas, thus quieting down the motorcycle.

The length of the baffle also affects its ability to dampen the sound. A longer baffle will usually be quieter than a shorter baffle.

Fiberglass packing can be wrapped around any baffle that does not already have one, thus further lowering the motorcycle’s sound. Other types of materials can also be used to wrap the baffle, for example, steel wall packing.

Often the baffles that come with aftermarket exhaust pipes can be very high pitched, making for a louder motorcycle.

What do motorcycle baffles do?

Motorcycle baffles are inserted into the exhaust pipe and force the exhaust flow to take a longer, indirect route instead of directly exiting the exhaust pipe. By doing this, the motorcycle baffle forces the exhaust flow coming out of the exhaust pipe to lose much of its pressure and thus quite down.

Motorcycles can be very noisy. In fact, they can be so nosy that they can be almost illegal to ride in some places. As a result, people had to find a way to keep the motorcycle’s noise acceptable and, most importantly, safe levels.

Some countries do not have any laws or regulations regarding how loud is too loud for a motorcycle. However, many countries do, and the actual noise ordinances will often differ from place to place. Usually, the laws will set an exhaust noise limit that can vary between 77 and 100 decibels.

Some countries may also forbid motorcyclists from tampering, removing, or even modifying their exhaust pipes and baffles.

Properly designed motorcycle baffles can create a deeper and richer rumbling exhaust sound.

The second thing motorcycle baffles do is to provide low levels of backpressure that the motorcycle’s engine needs in order to operate properly.

Does a motorcycle baffle affect the motorcycle’s performance?

Motorcycle exhaust baffles can affect the performance of the motorcycle. Motorcycle baffles affect the low-end and mid-range torque or power of the motorcycle, thus improving its performance and mpg. Motorcycle baffles can also affect the running temperatures of the engine.

Motorcycle baffles are designed by manufacturers to provide just a little bit of back pressure which is tailored to what the motorcycle’s engine needs in order to function properly. In others, the engine and the exhaust system are designed to work together as a unit.

This little bit of back pressure can prolong the life of the motorcycle’s engine and even give you a little extra horsepower.

On the other hand, motorcycle baffles are usually made to boost the motorcycle’s low-end to mid-range torque.

Removing the exhaust baffles will affect the performance of the motorcycle. By removing motorcycle baffles, you can lose a little of the low-end and mid-range torque. This can cause power dead-spots and slightly higher fuel consumption and lower mpg. Removing exhaust baffles can also lead to higher engine temperatures.

The dynamometer (dyno) will be affected as well.

However, rinstalling the baffle will return the motorcycle to its normal working conditions.

How much power you will lose will vary from motorcycle to motorcycle depending on the engine and exhaust setup and more.

However, if the baffle has been modified, cut, or otherwise altered in some way, reinstalling it can cause changes in how the motorcycle works.

The performance of fuel injected motorcycles may be less affected by removing their baffles, while carburated motorcycles may be more severely impacted by removing the baffles.

While a fuel-injected motorcycle may adapt to the change in the back pressure, carbureted motorcycles may start running lean, which can cause higher engine temperatures.

In any case, you will have to tune the fuel mixture to better accommodate the new flow generated by the change in back pressure.

How to find out if a motorcycle baffle does not work?

Seeing how motorcycle baffles are made from a simple rolled piece of metal, there is very little that can go wrong with them and cause them not to work.

There are a few things that can cause a motorcycle baffle not to work properly.

  • Rust and corrosion damage that has compromised the design and structure of the motorcycle baffle.
  • A motorcycle baffle that is not sized appropriately to the motorcycle exhaust it is installed in.
  • A motorcycle baffle that has severely worn out and damaged padding.
  • A motorcycle baffle cannot be installed securely to the motorcycle exhaust.
  • Poor quality welding on the baffle.

One of the problems that some riders may stumble upon is that sometimes the baffle may not come out easily and get stuck in the exhaust pipe.

In certain cases, the baffle can get loose and stuck inside the exhaust pipe, rattling while the motorcycle is running. A loose baffle can do a lot of damage to the exhaust pipe and should be removed and either replaced or secured properly.

Why people remove baffles on motorcycle exhaust?

A close up of a motorcycle's exhaust pipe with baffles.

People remove baffles on motorcycle exhausts to get a louder sound from the motorcycle. In addition to that, some people are under the impression that by removing their baffles and making their motorcycle louder, they will be safer while riding as other drivers will be more aware of them.

If there is no motorcycle baffle or the baffle does not work as intended, you can end up having one very loud motorcycle. Motorcycles can be between 80 and 110 decibels.

According to the CDC, hearing damage can start at noises as low as 70 decibels, depending on how long you have been exposed to those sounds. And at 95 decibels—which is a typical sound level for a motorcycle—hearing damage can start after 50 minutes of exposure.

This means that if you are running a straight pipe or the motorcycle baffle does not work properly for some reason, you are possibly causing damage to your ears.

There is also a common belief that “loud pipes save lives”, however, there is no concrete evidence supporting that statement, and the positive effect of a louder motorcycle on your safety is negligible at best.

Removing your baffles is not going to be bad for the motorcycle’s engine in most cases. However, removing the baffles does come with certain consequences like higher noise and possibly higher engine temperatures.

See article: Is it bad to remove baffles on a motorcycle?

Mike

Hello, two-wheel enthusiasts! My name is Mike, and I am the person behind motorcyclebrave.com. I am ready to go for a ride at any time of the day (or night). There is something about motorcycles that nothing else compares to. Here I share everything that I learn about motorcycles.

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