Exhaust is one of the most exciting systems on a motorcycle, and it is often discussed does it affect the way your motorcycle accelerates, sounds and drives. On the first hand, it might look like the exhaust is one of the easiest parts of a motorcycle to understand because it looks like pipes that lead the waste gases from the front wheel, but it does many other important things.
So how does a motorcycle exhaust system work? The exhaust system is responsible for the emission of exhaust gases from the engine into the environment. Exhaust gases pass through the exhaust pipes as the gas burns inside the engine from where they travel through the catalytic converter before being sent into the atmosphere.
Later in this article, we will cover many interesting things, so stay with us if you want to learn more.
Table of Contents
Motorcycle Exhaust Working Principle
Scavenging is one of the most important tasks done by the exhaust. It is a process where pressure waves are used to hold the fuel-air combination in the combustion chamber prepared for the spark, after which it helps to suck out the waste gases.
This effect is vital on two-strokes, although it is efficient on four-strokes too. The working principle on which it operates is the usage of the pulses high pressure liberated when the exhaust is released out of the combustion chamber.
Here is a nice video explaining how exhaust pipes work on 2 stroke engines:
If a fraction of these pulses can be sent out of the exhaust back to the engine at the right moment and there also happens to be some of the unburnt mixture left, the high-pressure wave will stop it from leaving before it is burnt. Conversely, the low-pressure wave will do the contrary, releasing burnt gases out.
The pulses need to be adequately timed, so both pipes must be the same length. The exhaust pipe diameters and lengths have to be perfectly measured to get this timing right since the waves move at the speed of sound, and it can be quite a challenge. This means that the rear pipe has to squiggle to cover the distance.
The exhaust lengths must be adjusted correctly since their working efficiency is best used on specific engine revs. We can conclude that exhausts are tuned to release the maximum power when you want it, such as bigger revs for race motorcycles or smaller revs in the case of cruiser motorcycles. They will both be inefficient if placed at the wrong extreme.
The most important purpose of the exhaust system is to send gasses out of the engine back into the air.
Note: The exhaust pipe’s purpose is to assist the engine in running fluently by bringing the backpressure across the cross-sectional area and pipe length.
The exhaust pipe has broadened parts of where these gasses will pass through. Because of this broadening part of the exhaust pipe, the exhaust gasses can expand and create backpressure which sends a pressure wave back to the motorcycle engine.
The backpressure travels to the cylinder, and once it gets there, it makes a pressure differential at the cylinder. Because of this operation, the engine runs more smoothly. Many riders don’t give much attention to backpressure, which is not very smart since this is important, especially when you want to decelerate. What happens is that your engine starts to backfire as you decelerate.
Note: If your motorcycle had issues with backpressure, this would present a significant problem because you would make fewer miles with the same fuel amount, and not only that, but your motorcycle would also run not as efficiently as it usually would.
Many riders decide to change their stock exhaust with the customed one. One of its benefits is reducing motorcycle weight; the other benefit is creating better airflow, so more backpressure can be released, which affects the engine work quality, which gets better, of course.
Here is a great article about Motorcycle Sound and How Exhaust System Affects It, so click on this link to learn more.
Riding without the Motorcycle Exhaust Pipe (Is It Good or Bad)
When we were kids, we used to do many crazy things with motorcycles, and riding without an exhaust pipe was one of them (although with today’s knowledge, I wouldn’t do the same).
Tip: I would advise you not to do the same because this is illegal in some states (depending on where you live, but in most states it is not legal to drive without exhaust), you can harm your motorcycle, and the reason that probably most of you want to know is if you get any increase in your motorcycle performance and power, the answer to that question is that it doesn’t improve your motorcycle performance.
If you want to make adjustments to your exhaust system, the best way is to create a customed exhaust system that will be made perfectly just for your motorcycle make and model.
Professional Tip: Hire a professional expert with a decent history of making exhaust systems and tell him your desires and what would be best for your bike.
If you want to learn How to Repair Your Motorcycle Exhaust Pipes, click on this link.
What Function Does a Cat (Catalytic Converter) Have?
A catalytic converter or so-called cat is a box placed beneath the engine, often connected with the collector where the header pipes merge. The inner side consists of a honeycomb of precious metals such as platinum. Their purpose is to create a reaction among the exhaust gases that turn them into carbon dioxide and water vapor.
Although it is smart, it seeks precise conditions to function correctly, and the fuel injection can be placed to make the right conditions.
Note: If you decide to remove the cat, it has two benefits. It will remove restrictions, save you a lot of weight, and allow the exhaust to run more freely.
Silencer or End Can
A silencer or an end can is a part of a motorcycle exhaust pipe made of bent barriers where low and high-pressure pulses bounce, and by doing so, they cancel mutually and create a softer motorcycle sound.
Here is a great article about How to Repair Motorcycle Exhaust Pipes, so click on this link if you want to learn more.
Can You Improve Your Motorcycle Performance by Changing Your Exhaust?
It is possible to improve your motorcycle performance with exhaust changes, and such modifications are very popular among riders. There are a few segments of your motorcycle exhaust system that you can modify.
Modifying Exhaust system includes:
- Switching stock systems header
- Switching motorcycles complete exhaust
- Replacing stock muffler with a slip-on muffler
- Placing heat shields to exposed exhaust pipes
Performance
The engine power in four-stroke engines can be increased by lowering the exhaust backpressure. The horsepower can be increased by adding the exhaust with more free-flow space since it creates more exit space for fumes and gases. Some motorcycle weight can be reduced by adding another exhaust, affecting overall performance.
Sound
A good quality sound insulator can reduce the stock exhaust while increasing the outlet diameter increases sound.
Appearance
Exhausts made out of titanium chrome and painted in many color variants can make a lot of difference in appearance.
Final Thoughts
Every motorcycle is unique, which means that it requires a specific and unique exhaust system. I have witnessed some riders with exhaust pipes that looked good to them, and honestly, the bikes looked amazing with them, but the problem was that that exhaust pipe was not suitable with their motorcycle make and model. That means that other than amazing visual effects, the rider had no use of it in a matter of gaining extra horsepower because that pipe was made for another bike mode. However, I must confess that his bike sounded pretty impressive (it was Yamaha R1 from 2013).
With that being said, my advice to you is to do your own research on what exhaust system (and that includes exhaust pipes as well) suits your bike the best. If you do that, I guarantee you that not only will you have the fantastic sound of your motorcycle, but you will also gain that extra wanted horsepower.
I hope you enjoyed this article.