Can Aftermarket Exhaust Damage Engine on Motorcycle?

Lots of motorcyclists choose aftermarket exhausts to maximize their bike’s performance. It’s true: getting a specially designed aftermarket exhaust manifold can get maximum horsepower and RPMs from your bike’s engine.

Customization and modification always open up a huge array of possibilities — you can fine-tune your two-wheeler to give you exactly the kind of ride you want.

As with any aftermarket modification, changing your exhaust valves or getting a new exhaust system comes with its fair share of risk.

Can Aftermarket exhaust systems damage my motorcycle engine?

Yes, aftermarket exhausts have the potential to damage your motorcycle if not entirely compatible with your engine or not installed properly. Although they can boost performance and fuel economy, here’s what to look out for in case your engine backfires:

  • Gapping issues in spark plugs or ignition
  • Insufficient engine compression
  • Too much backpressure and decreased fuel economy

Here’s a premium aftermarket exhaust system with a catalytic converter and stock exhausts to consider.

Top 3 Motorcycle Engine Issues that may occur due to Aftermarket Exhaust Modifications

can aftermarket exhaust damage engine

Here are the most common issues that motorcyclists face after installing an aftermarket exhaust system:

Reason #1: Gapping Issues in Spark Plugs or Ignition

One of the most common problems that can happen to motorcycles with an aftermarket exhaust is backfiring. This could occur when the spark plug has not been properly gapped or there’s a problem with your carburetor or ignition system settings.

Backfiring can occur anytime even if you are idling the motorcycle engine, without any warning. The engine could stall all of a sudden. Another tell-tale sign is when your engine starts to flood, there’s a strong smell of gas, or cylinders are misfiring.


Aftermarket exhausts can cause an engine that’s running lean. This leads your spark plugs to malfunction. With insufficient gas in the combustion chamber being injected by the carburetor, temperatures rise higher than normal due to more air intake. This warps the spark plugs.

You’ll have to inspect your spark plugs to see if they’re rusted, broken, warped or simply giving way due to wear and tear. Once you’ve replaced them, ensure that they’re fitted properly. Not all spark plugs are pre-gapped.

Reason #2: Insufficient Engine Compression

With an aftermarket exhaust, you will also need to check the engine compression because it might be lower than what is required according to your stock exhaust system. This happens when you use a spark arrestor or slash-cut exhaust that can cause a backfire and makes your engine lose power.


It’s always a good idea to check your motorcycle compression so you avoid using an incompatible exhaust system. Here’s how to perform a compression test when your engine is hot:

  • Switch off Petcock and remove the fuel pump fuse, as well as all spark plugs and the equipped ignition fuse.
  • Use a compression tester on the cylinder, with your O ring hooked up to the adapter.
  • While holding the crank open, kickstart your motorcycle and record the value till the needle stops climbing. Now you can compare this to the recommended value in the service manual.

Reason #3: Too much back pressure and decreased fuel economy

Another disadvantage is that the backpressure might not be in sync. This occurs when too much air escapes from the engine, which can cause it to idle poorly or decrease fuel economy even if there is more power at higher RPMs. As such, motorcycle exhausts are often designed to maximize performance and power without causing too much backpressure.


Choosing an exhaust system with fewer bends, longer length and diameter, and a muffler can contribute to the amount of backpressure while getting more horsepower out of your engine system easily.

Pros and Cons of an Aftermarket Exhaust for Motorcycles

The Pros

1. Weight Reduction

The main advantage of a motorcycle exhaust is that it reduces weight. Aftermarket motorcycle exhausts are often lighter than the stock exhaust, which means that they remove excess weight from the bike.

This can improve acceleration, braking, and handling while increasing fuel efficiency. They can also decrease the total weight of the motorcycle by several pounds.

2. Increased Performance and Horsepower

A motorcycle exhaust also increases the engine performance by reducing back pressure, which allows air to escape more freely from the engine. This can lead to increased horsepower and torque as well as improved fuel efficiency.

The result is a faster motorcycle with an increase in power throughout the entire RPM range (not just at peak).

3. Smoother Engine Operation

Another benefit of a motorcycle exhaust is that it can reduce engine rattling and other sounds which may be annoying. As such, aftermarket exhaust is often preferred over the stock unit for those who want to enjoy their ride or not annoy those around them.

A benefit shared with increased performance and horsepower is a smoother engine operation.

4. Increased Fuel Efficiency

An additional benefit of an aftermarket motorcycle exhaust is that it can increase fuel efficiency by reducing the total weight of the motorcycle and allowing for more free airflow which takes less energy to shift through the engine.

Less unsprung weight = lower fuel consumption or higher miles per gallon.

The Cons

1. Additional Expense

The main disadvantage of an aftermarket motorcycle exhaust is that they are often more expensive than stock units. This means that it can be too costly for some riders who simply want to improve the looks or sound of their bike.

It should not be surprising that performance parts will cost more than regular OEM parts.

2. Durability

Another issue with some aftermarket exhausts is that they are often not as durable as the stock unit. This means that it might be more prone to damage and parts tend to break faster than normal. As such, some newer riders might want to avoid an aftermarket motorcycle exhaust so that they don’t have to pay for repairs as often.

OEM (Original Equipment Manufacturers) stock exhaust systems tend to have warranty and replacement guarantees which aftermarket alternatives don’t. However, for the power increase, and free flow of exhaust pipe air — the performance boost seems to be worth it.

3. Not enough Weight Reduction

Lastly, an aftermarket motorcycle exhaust will not reduce weight as much as other aftermarket parts (such as handlebars or wheels). This is because the stock unit already reduces weight while lowering weight further can make a bike dangerous and difficult to ride due to poor handling.

As such, a motorcycle exhaust is not as ideal for weight reduction as other aftermarket parts.


In conclusion, aftermarket motorcycle exhausts have several advantages that can improve performance and fuel efficiency while reducing weight. You can even ask for a license from the Bureau of Product Standards so you can make sure that your motorcycle is street legal, with the required emissions and safety standards for you to pass inspection.

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