Do You Have To Tune Motorcycle After Installing Exhaust?

The question that always comes to mind before installing an exhaust is tuning. Do you really need it? Some say you do, while others say you don’t! 

In this article I want to discuss all about exhaust and tuning. Make sure you understand what really happens inside so you can agree with me whether tuning is required or not! 

For a quick answer – you don’t have to tune your motorcycle if you are installing a slip-on exhaust. However, you have to tune or at least recommended to – if you are installing a full system exhaust. 

Now let’s discuss that short answer in more detail. Beginning with why tuning is only needed on a full system and how tuning works for different motorcycles.

Tuning is not required for slip-on exhausts because they do not create a big enough impact on the exhaust flow or any other critical components. Enthusiasts install slip-on exhausts only for the looks and sound not performance. 

Slip-on exhausts only replace the “end can” of the exhaust. Which means only a portion of the exhaust system is replaced – mainly the muffler. 

Slip-on exhaust installation will not touch critical components like O2 sensor or catalytic converters (CAT). Which means, your motorcycle’s computer will not be impacted much. Your motorcycle will run the same and you won’t see any warning lights on the dashboards!

Slip-on exhaust is a great choice if all you care about is a better sound and looks for your motorcycle. They are cheap, easy to install and do not require any tuning. Just slip it on and clamp it down – you are good to go. 

If you also want performance, then you will need to look into a full system exhaust. This however, will require tuning. Let me explain.

Slip-on Exhaust

Tuning is required for a full system exhaust because they improve the flow of gases in your motorcycle significantly. Thus, increasing the amount of oxygen in the combustion chamber.  

You need a tune – mainly to increase the amount of fuel injected into the combustion chamber. Otherwise, it will be a bottleneck to your HP gain – you only have extra air from the exhaust but not enough fuel to burn all of the air.  

Did you get that? Let me explain more.

A full system exhaust replaces everything in your stock exhaust starting from the mid-pipe to the tail. Which means, you will get below components:

1. Less restrictive piping throughout
2. Less restrictive catalytic converter (CAT)
3. Less restrictive muffler

Full system exhaust.

When you replace the entire exhaust piping into wider and less restrictive ones, it will make exhaust gases flow quickly. This is important because the quicker the exhaust gases leave, the more room is available for air in the combustion chamber.

I will explain more about combustion later. For now – know that your motorcycle engine creates combustion to deliver power to the wheels. This combustion requires both air and fuel and it also generates toxic gases as a byproduct.

If you want more power, you need more air and fuel. With a less restrictive exhaust piping, exhaust gases will leave quicker and give more room for air to enter. 

This means the combustion chamber now has more air but still the same amount of fuel! You need to tune your motorcycle to inject more fuel to create that perfect and bigger combustion.

Air and fuel must be in a perfect ratio to create powerful combustion. Upgrading the exhaust alone without tuning is increasing the amount of available air but with the same amount of fuel! You will not achieve maximum power gain.

Aside from just power gain, you also need tuning to disable the warning indicators on your dashboard. Full system exhaust may contain a less restrictive CAT. It can result in more power but in turn gives out more emission.

Your motorcycle’s computer might detect this and throw you a warning. A way to keep it off is through tuning. 

I hope you now know why your new exhaust might need tuning. If that was too much to digest, I totally understand. I will be talking more about combustion now – this should clear things for you.

A motorcycle engine is a combustion engine – which means it delivers power by creating an explosion using air and fuel. This explosion also generates toxic exhaust gases that must exit the motorcycle. 

Air is sucked from the surrounding through the motorcycle air intake, whereas fuel is injected to the combustion chamber. 

The more horsepower you want, the more air and fuel you will need. Installing an aftermarket exhaust will help increase the amount of available air in the combustion chamber. 

This is because an aftermarket exhaust system is less restrictive – it allows exhaust gases to flow better and leave quickly. The faster the exhaust gases leave the combustion chamber, the more air can enter for the next combustion cycle.

However, you only have half of the equation! You still need to tune your motorcycle engine to provide more fuel into the combustion. Then only will you get extra horsepower. More fuel and air remember? Not just more air!

There are two ways to tune a motorcycle air / fuel ratio – depending on what kind of fuel management system is installed on your motorcycle. There are two variations:

1. Fuel Injector
2. Carburetor

They both provide fuel into the combustion chamber but work a bit differently. The tuning process varies depending on what’s used! 

Let’s talk about them.

Carburetor 

Carburetor is a device that’s usually found on older motorcycles. It mixes air and fuel through a mechanical way. It does not need electricity for power and does not need any computing power to operate.

Carburetor is directly connected to your motorcycle throttle. As you accelerate, the throttle opens up to let air through and use air pressure difference to allow the right amount of fuel into the combustion chamber.

You don’t have to know how carburetors work exactly. What you need to know are these things:

1. Carburetor are usually found on older motorcycles
2. Carburetor works through a mechanical way – no electricity required
3. Carburetor does not use computer to function

If you want to tune a carburetor AKA “carb”, you have to purchase a jet kit. There’s no programming or flashing required (like tuning a car would).

Motorcycle carburetor

Fuel Injector

Fuel injector is used in most modern motorcycles. It uses sensors and computing power to measure how much air is coming (or should come in) and then spray just the right amount of fuel for the perfect combustion. 

Fuel injector is much more efficient – there won’t be any wastage of fuel. Since it’s controlled  through a computer, a fuel injector system won’t be impacted by weather or altitude. 

These are external factors that will impact a carburetor. For example, your carb motorcycle will run differently when you are in the mountains. 

Again, you don’t have to know exactly how a fuel injector works. What you need to know are these things: 

1. Fuel injectors are found on new motorcycles
2. Fuel injectors are not the standard
3. Fuel injectors work using a computer

Now that you know the difference between carburetor and fuel injector, we can discuss how to tune them.

Tuning a carburetor engine is different from tuning a fuel injector engine. Carburetor works through a mechanical way (analogue). Whereas fuel injector works using a computer (digital).

Keep in mind that when you install a performance mod like exhaust, there’s more air in the combustion chamber. You need to tune your motorcycle to increase the fuel intake so you have the right air / fuel ratio and get more horsepower.

Tuning Fuel Injector

There are two ways to tune a fuel injector:

1. Purchase and install Power Commander
2. ECU Flash

Power commander is a device that is hooked up to your motorcycle’s computer and changes its settings. You could choose the settings that fit your need and have it installed on your Power Commander. These settings are called maps and can be downloaded from the internet. 

The power commander will be installed on your motorcycle and will stay installed on the motorcycle. 

ECU flash is where you bring your motorcycle to a dyno and have them manually reprogram your motorcycle’s computer (ECU). You could go much more than just Air / Fuel ratio – things like ignition timing, throttle response and disabling warning indicators.

Both are an option. But if you are a beginner, purchasing and installing a power commander is the easiest route. 

Tuning Carburetors

To tune a carburetor, you need to purchase and install a Jet Kit – typically a larger Jet because you need to insert more fuel into the combustion chamber for more power.

Everything here is mechanical. There’s no fine tuning or download and installing other people’s settings. 

With tuning, expect to add another 5 horsepower on top of what you get just from the exhaust alone – totaling to 12 horsepower.

The actual horsepower of course depends on your motorcycle engine. The bigger the engine, the more potential it has to rise. 

I have an article here where I discuss the horsepower gain from installing an exhaust. I cover the HP gains you should get from a slip-on exhaust, full system and full system with tuning.

Check it out. How Much Horsepower Does Exhaust Add To a Motorcycle?