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A Complete 101 Guide to Motorcycle Exhausts (Purpose, Parts, and Types)

A Complete 101 Guide to Motorcycle Exhausts (Purpose, Parts, and Types)

The exhaust system is an essential motorcycle component that improves performance, aesthetics, and the sound of the engine. You can improve engine performance by installing a good-quality exhaust system that directs burnt gases out of the combustion chamber. Read this article to learn about motorcycle exhausts, including their types, parts, and maintenance.

1. The Purpose of the Motorcycle Exhaust System

The motorcycle exhaust system ensures a quieter riding experience and improves engine performance. The purposes of a motorcycle exhaust system include the following:

1.1 Removes Exhaust Gases

Removes Exhaust Gases

An exhaust system is connected to an engine to remove gases from the combustion chamber. It provides a channel for hazardous gases to travel through and expel at the exhaust. The exhaust pipes are installed to protect your legs from being burned by the heat of the engine.

1.2 Reduces Noise

Motorcycle exhaust pipes are fitted with mufflers/silencers at the end to reduce the noise from the engine. The muffler attached at the end of the exhaust pipes causes the gases to expand that muffle any noise as they are expelled. The linings and perforations in the muffler also help lower the volume of the engine.

1.3 Improves Engine Performance

Motorcycle exhaust pipes are made of insulating material that keeps heat inside and makes the gases pass through the system quickly. This ensures constant airflow that puts less stress on the engine and improves efficiency.

Also Read: How to Heat Wrap a Motorcycle Exhaust

1.4 Helps Meet Emission Standards

Modern exhaust pipes are equipped with catalytic converters that convert harmful gases like carbon monoxide into less toxic emissions like carbon dioxide.

2. How Does the Motorcycle Exhaust System Work?

How Does the Motorcycle Exhaust System Work

The basic function of an exhaust system is to expel all the gases from the engine. These gases are produced by burning an air/fuel mixture in the combustion chamber. Exhaust headers are connected to the engine cylinders and transfer the gases to the exhaust pipes.

There are several sections and parts throughout the exhaust system that perform different functions. The sections in the exhaust pipe causing the gases to expand, sending some of the pressure back to the engine, known as back pressure. The back pressure creates a pressure differential in the engine which improves low-end performance and fuel efficiency. If the exhaust system cannot produce back pressure, it will cause the engine to backfire during deceleration.

A straight or drag exhaust pipe does not allow the gases to expand due to there being no back pressure produced. These drawbacks make motorcycles with drag pipes consume more fuel and reduce idling and low-end performance. However, they can produce better horsepower.

2.1 Motorcycle Exhaust System Parts and Their Functions

Motorcycle Exhaust System Parts
Parts Description
Exhaust Headers Attached to the engine
Receives gases from the engine
Reduces exhaust pressure to some extent
Transfers the gases into the collector
Exhaust Collectors Receives gases from the header
Helps convert toxic gases into reduced emissions to some extent
Catalytic Converters Emission-control devices
Placed inside the connector pipes and exhaust collector
Catalyzes the redox reaction
Converts toxic gases into reduced emissions
Converts carbon monoxide into carbon dioxide
Lambda Sensor Located in the collector
Measures the amount of oxygen in the exhaust pipe
Calculates the proportion of air in the air/fuel mixture
Provides feedback to the engine about fuel consumption
Can help reduce fuel consumption
Butterfly Valve Located behind the silencer/muffler
Controls the flow of gases
A servo motor-operated valve that can reduce noise
Silencer/Muffler Helps reduce noise produced by the engine
Expels gases from the system into the environment
Gives motorcycle a sportier look
DB Killer Installed near the exterior of the muffler
Reduces frequency of sound waves coming from the exhaust pipes
Redirects the sound waves toward the exhaust pipes

3. Types of Motorcycle Exhaust

Different types of motorcycle exhausts have unique characteristics and features. Replacing the stock exhaust with an aftermarket version can affect the performance, weight, and sound of the engine.

3.1 Single/Drag/Straight Exhaust Pipe

Single/Drag/Straight Exhaust Pipe

A straight or drag exhaust pipe is a single extended pipe attached to the engine cylinder to protect the rider and passenger better. It can come in multiple styles and shapes and is usually installed with a baffle. A baffle is a perforated small pipe placed inside the exhaust pipe to control the back pressure and reduce the volume of the exhaust. Some riders love the loud sound created by a drag exhaust pipe without a baffle, but this can reduce back pressure that could damage and reduce engine performance.

3.2 Separate Dual Exhaust Pipes

Separate Dual Exhaust Pipes

Separate dual exhaust pipes are heavier than the single drag pipe and usually installed on powerful, bulky heavyweight motorcycles powered by large-displacement engines, such as touring bikes and cruisers. Separate dual exhaust pipes are usually attached to V-twin engines, allowing them to separate the gases from both cylinders. Keeping the gases from both cylinders separate promotes better airflow and reduces shock.

3.3 Two-Into-One Exhaust Pipe

Two-Into-One Exhaust Pipe

A two-into-one exhaust system helps improve performance in several ways. Firstly, it is lighter than dual exhaust pipes and two-into-two exhaust pipes. Secondly, the rider can lean the motorcycle when turning a corner without scraping the muffler. A two-into-one exhaust pipe improves a motorcycle’s performance by reducing back pressure.

3.4 Four-Into-One Exhaust Pipe

Four-Into-One Exhaust Pipe

Photo Credit: Motorcyclist Online

A four-into-one exhaust pipe has four headers connected to four cylinders on the engine that merge into a single collector and muffler. This exhaust system is not commonly found on modern motorcycles. The four-into-one exhaust pipe was widely used in the 1970s when Japanese four-cylinder motorcycles became popular. This exhaust system is lightweight and greatly reduces the overall weight of the motorcycle. During the 1970s, motorcycles with four-cylinder engines had poor handling due to being fitted with four exhaust pipes. The four-into-two exhaust pipe provided better handling and greater lean angles for motorcycles with four-cylinder engines.

3.5 Four-Into-Two Exhaust Pipes

Four-into-two exhaust pipes have four headers connected to the four cylinders that merge into two separate collectors and exhaust pipes. This exhaust system is heavier than the four-into-one exhaust system. However, they are not common and are installed on only a few motorcycles.

3.6 Slip-On Exhaust

Slip-On Exhaust

Photo Credit: Graves Motorsports

A slip-on exhaust is a can-shaped pipe with a muffler attached to the exhaust system. It helps reduce weight, provide a sporty look, and produce a louder exhaust note. Slip-on exhausts are also cheaper and easier to install. However, slip-on exhausts do not increase horsepower and torque.

Also Read: Easy Ways to Improve Motorcycle Engine Performance

4. Pros and Cons of Aftermarket Exhausts

Pros of Aftermarket Exhausts Cons of Aftermarket Exhausts
Improve look Excessive air and noise pollution
Improves performance Illegal in most countries
Customizable May not comply with emission standards
The loud and attractive exhaust note Installing an aftermarket exhaust may nullify your motorcycle’s warranty
Better fuel economy
Better flow of gases
Increases horsepower and torque

5. How to Choose the Best Exhaust Pipe for Your Motorcycle

There are various types of motorcycle exhaust pipes and configurations you can use to replace the stock exhaust system. Replacing the exhaust pipe will alter your motorcycle's look, noise, and performance. There are several factors you should consider before choosing an exhaust pipe for your motorcycle, including:

5.1 Exhaust Pipe Material

Exhaust pipes are often classified based on what material they are made from. Titanium and carbon fiber exhausts are the most popular yet expensive exhaust pipes due to their being extremely lightweight, able to withstand high temperatures, and ensuring better engine performance. However, if you are working on a tight budget, aluminum and stainless steel exhaust pipes are the best options.

Types of Exhaust Pipes Based on Material
Exhaust Pipe Benefits
Chrome Steel Moderate price
Improves look
Durable
Long-lasting
Stainless Steel Cheap
Durable
Long-lasting 
Aluminum Cheap
Lightweight
Corrosion-resistant
Good heat conductor
Titanium Expensive
Extremely lightweight
Durable
Rustproof
Good heat conductor
Quick heat dissipation
Carbon Fiber Expensive
Extremely lightweight
Heat-resistant
Improves engine performance
Improves flow of exhaust gases

5.2 Exhaust Pipe Configurations

An exhaust pipe configuration can affect a motorcycle’s performance, weight, and aesthetics. The exhaust configuration best suits your motorcycle depends on the model and engine. For example, a motorcycle powered by a V-Twin engine will perform better if fitted with a two-into-one exhaust system than a two-into-two exhaust system. Removing a muffler reduces the weight of the exhaust system and increases torque. Prioritize exhaust pipes that improve performance and reduce fuel mileage rather than produce a loud noise and improve the look.

5.3 Muffler Designs

Mufflers are available in several designs to satisfy different rider preferences. Some people prefer a carbon fiber slip-on exhaust that gives their motorcycles a sportier look, while others prefer extended mufflers with slash-cut ends, fishtails, and cigar mufflers.

6. Takeaway

Motorcycle exhaust systems are categorized by their configurations, designs, and materials. Changing the motorcycle exhaust pipes can alter your motorcycle’s weight, noise, and performance. You can determine which exhaust pipes best suit your motorcycle based on the engine and model. Whichever exhaust system you choose to install, make sure it is environmentally friendly, reduces noise, and complies with emission standards.

If you want to customize your motorcycle to improve its comfort, safety, aesthetics, and performance, Viking Bags offers a wide variety of aftermarket motorcycle parts. These include sissy bars, crash bars, fairings, handlebars, seats, and backrests. You can also improve your motorcycle’s storage capacity by installing sissy bar bags, saddlebags, tour packs, and tank bags.

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