Triumph tuning guide

How you tune your bike depends on what type of fuel system your bike is fitted with. For Triumphs, it breaks down into Carbureted or Fuel Injected models. This guide is separated into three sections


  • 2001-2007 Air Cooled Triumph Motorcycles (Carbureted) 
  • 2008-2017 Air Cooled Triumph Motorcycles (Fuel Injected)
  • 2016-Up Liquid Cooled Triumph Motorcycle (Fuel Injected)

In each section we’ll describe the fuel system and best practices for tuning your Triumph Motorcycle. 

LEGAL DISCLAIMER: It’s your responsibility to check about the legality of certain performance parts and tunes in accordance to where you live. Changing your bike’s stock tune can change its emissions rates, which is illegal in some states (including the state of California). Modifying your bike’s tuning can also nullify factory warranties.

Introduction & basics

As you make adjustments and modifications to your Triumph, there are certain modifications that will change your bike significantly enough to need a tune in order to get the most out of it.

We’ve put together this basic guide as a starting point resource to find out what a proper tune can do for you, when you will need to tune your Triumph depending on your model and modifications, and also give you general parameters of methods of tunes to use as applicable to BC products and your Triumph model.

Before we get into it we do want to state that tuning your bike will be useless if your bike isn’t properly maintained. Many issues that are thought to be a tuning issue are actually maintenance issues. So make sure that your bike is in good shape before you think about a tune.

This guide will also not apply if you’ve changed your engine significantly (big bore, cams, headwork). 

First, let’s break down some basics to help you understand what a motorcycle tune is.

In simple terms, a motorcycle engine generates power with a mix of fuel, air, and spark. Spark “ignites” the fuel and air mixtures within the cylinders to cause timed combustion cycles (literally explosions), which are then turned into mechanical power to move the vehicle.

Motorcycle engines will perform differently if changes are made to the conditions and ratios of fuel:air in these combustion cycles. Better balanced explosions from the correct ratios between fuel and air = a smoother acceleration experience and less drag. Bigger combustion explosions from more fuel balanced with better air flow = more power. Basically, a bike can significantly perform better if combustion ratios are optimized for your setup.

If you make modifications to your bike without adjusting its tuning, you can cause imbalances to the ratios of fuel:air in your bike and your bike will begin to perform poorly or can even cause damage to itself. You may stumble when accelerating, experience lag when you need speed, or hear your engine cough, sputter, or backfire. In the worst cases, you can damage your engine without a proper tune, especially if you run it lean. 

This is where tuning your motorcycle comes in. Tuning makes changes and tweaks to optimize the balance between fuel, power, and air throughout your entire powerband to get the most out of your bike as well as the modifications you are making to it.

Generally, whenever you make upgrades to the engine, intake or exhaust, you need to tune your bike because a change to any of these areas will affect everything we talked about above.  

British Customs products currently offer upgrades to the intake and exhaust aspects of the engine, basically affecting the air part of the engine equation. Our upgrades will increase the amount of air flow in your engine, which will change the ratios between fuel:air. 

Intake refers to the air (O2) going into the engine, where it mixes with fuel and is ignited with spark to power your bike. Think “inhale” - intake upgrades will determine the quantity and quality of the air that is sucked into the engine cylinders. 

Exhaust: Exhaust refers to the waste gasses and other combustion products exiting the engine. Exhaust systems can change the way and rate of how quickly these gasses are sucked or “scavenged” out, which helps the chamber to intake with more oxygen faster to allow for bigger combustions and more power. 

Pay attention to how your bike is riding: 
One method would be to look out for some things while riding. Feel for flat spots when you’re moving and notice if certain parts of your powerband dip or plateau at certain RPM ranges. Also take note if it feels like your bike lags while throttling - it will feel like there’s a disconnect between your throttle and your bike’s responsiveness to it. 

There are also a few symptoms you can look out for to tell if your bike is running too “lean” or too “rich”: 

Lean (too much air):

- Frequent backfire (“popping”)

- Engine overheat

- Throbbing acceleration despite consistent throttle

- Delay in Response

- White-ish residue around the spark plugs after riding

Risks: Running your bike lean poses the biggest risk to your engine, since the lack of fuel will make the combustions run hotter, and the lack of lubrication + heat causes more friction that wears fast on your engine’s internal parts

Rich (too much fuel):

- Strong fuel odor

- Bike is consuming fuel fast

- Dirty air filter

- Black residue around the spark plugs and exhaust

Risks: Running your bike rich is not only terrible for performance and wasteful on gas but can cause your engine to clog with sediments due to the excess amount of unburnt fuel sitting in all parts of your engine.

Dynamometer Testing: 
Another way to find out if you need a tune is by finding a Dynojet approved tuning center and putting your bike on a dynamometer to provide you with detailed data and graphs showing you where your bike needs adjustments with surprising precision. This is also another good way to diagnose your bike to see if there are any mechanical issues.

Use a third-party tuning software to view your tuning maps (for fuel-injected bikes):
If you have a fuel-injected bike, you can use third-party tuning software to plug your ECU in and view your actual tuning map. But we don’t recommend making your own changes to your map unless you know what you’re doing as you can seriously damage your engine with an incorrect tune. Finding a professional tuner to create a custom map for you is the best way to get the most out of your bike.


Triumph released the Air Cooled Parallel Twin in 2001, a carbureted engine fueled by two 36mm Keihin CVK Carburetors. (The following will only apply for the stock Keihin carb, so if you have a Mikuni carb or any other brand, this information will not apply.)

A carburetor is found on older bikes, and is the part of the engine that determines the amount of fuel that is let into the engine. It can only be manually adjusted.

A complete tune for a carbureted bike may require work to any component that changes the air, fuel, and spark (i.e. replacing air filter, changing spark plugs) but we will be talking specifically about rejetting, having more to do with adjusting fuel to air ratios, which is more relevant to BC’s intake/exhaust upgrade products.

In order to better understand the guidance chart we have below for carbureted bikes, we’ll cover some more basics below. 

The jets in a carburetor are brass nozzle parts that have holes or openings through which fuel is let into the engine. There are two fuel jets in a carburetor: the pilot jet and main jet

The pilot jet is the smaller of the two, and it has a very small hole through which the natural engine vacuum sucks fuel out of continuously when it’s running. Whenever you are idling or at the first 15-20% of your throttle turn, the pilot jet is the part that’s letting fuel into your engine, so it is kind of always letting fuel into your bike in the background as long as your bike is on.

Now imagine you’re idling, and then you put your bike into gear to begin rolling forward. As your bike goes into motion and you get into a mid to full throttle turn, a needle inside the carb that was serving as a stopper in the main jet hole is raised upwards out of the hole by you turning your throttle, and fuel is now able to pour into the engine through this hole. The size of the main jet opening will determine how much fuel comes into your engine when you activate the throttle in the mid to higher ranges of your powerband.

In order to rejet your bike, you need to change out the pilot or main jets for ones with different size openings, depending on your needs. The number on the jets identify the size of the opening. If you need more fuel, go up in number and vice versa. 

Another way to adjust your carb is by shimming the needle. A shim is a spacer that will make the needle stopper that usually blocks the main jet sit a little higher, moving the transition point for when the pilot jet passes over to the main jet. A shim will also enrich the entire fuel circuit.

Air Mixture Screw:
This is a screw that you can access from the outside, and turning it will increase or decrease the amount of air that is allowed into the carburetor in your low to mid ranges of your powerband. You adjust the screw while the engine is running, and first turn it all the way in, and then turn it back out a specific number of rotations depending on your need. It’s usually best to turn it just until the point that you hear the idle start to elevate. 

There are a lot of factors that can affect the tuning of a carbureted motorcycle.

The main two reasons are: 

- Changes in weather, humidity, atmosphere, and altitude

- Making significant upgrades to the bike 

For the purpose of this British Customs tuning guide we are focusing on what to do for upgrades to the intake and exhaust, and typical BC upgrades that require tuning the bike are as follows:

- Intake (Air Filter, Air Box Removal Kits, Snorkel)

- Exhaust (Slip-ons, 2-1 Full Systems, 2-2 Full Systems)

Carbureted Tuning Chart

For 2001-2007 Air Cooled Triumphs with British Customs Slip-On Exhausts, Full Systems, and British Customs Performance Packages (Slip-On Exhaust or Full System + Air Box Removal Kit + Air Injection Removal Kit). The guide provides the recommended range of main jet, pilot jet, shims and air mixture screw settings.

Please note that the jetting recommendations have been tested at sea level (if you are above or below sea level you will have to update the jetting accordingly).


In 2008, the Triumph Air-Cooled Parallel Twin fuel system was upgraded to a Keihin fuel injection system. Visually, the upgrade is almost unnoticeable because the fuel injectors are hidden within a carburetor-shaped enclosure, but the differences between how these two systems work is huge.

The quickest way to identify if your bike is fitted with fuel injection is that the carb-shaped enclosure will read "CTK"

In regards to tuning, the main difference about fuel injected vs. carbureted bikes is the presence of a computerized ECU/ECM (Electronic Control Unit/Engine Control Module) system that can be loaded with programmed tuning maps. Because the adjustment of the engine’s fuel:air ratios is computerized, tuning for fuel injected Triumphs means downloading or creating tuning maps for your ECU - “remapping” instead of manually adjusting it.

While having an ECU in the air cooled fuel injected models makes this fueling system more precise and “smart,” it cannot adjust for everything and is dependent on a tuning map that works with your bike’s set up.

For example, let's say you install a new BC exhaust onto your stock Triumph. Without a new map, there is nothing to tell the bike that it now has a higher flowing exhaust, and it will continue to follow the previous map designed for its stock exhaust, making it run lean.

Unlike the newer liquid cooled models, air cooled fuel injected Triumphs don’t have the ability to adjust to even smaller upgrades, so you will need to remap your bike whenever you make any upgrades to your intake, exhaust, or engine.

This line of Triumphs does however adjust for smaller changes in weather, altitude, and humidity, since it is equipped with O2 sensors that monitor the levels of oxygen in your engine and sends this data to the ECU to make minor adjustments.

Typical British Customs upgrades that require remapping the bike are as follows: 

- Intake (Air Filter, Air Box Removal Kits, Snorkel)

- Exhaust (Slip-on, 2-1 Full Systems, 2-2 Full Systems)

There are a lot of options for remapping your air cooled fuel injected Triumph, and they largely break down into preset maps/tunes and customized maps/tunes. 

You can think of a preset map as a “one size fits all” cookie cutter approach, and there are many maps available both from Triumph dealerships or on the aftermarket designed for various bike set-ups that you can install to your ECU/ECM by using a third-party tuning software (ex. Tune ECU). You just have to make sure that the maps you’re installing are compatible with your set-up, otherwise an incorrect tune can create running issues or even cause damage to your bike. If you’re unsure of what maps you may need, you can contact your local Triumph dealer or talk to a professional tuner.

A customized map is different in that it is bespoke to your specific bike and modifications, fully optimized for your specific set up as well as to the weather, altitude, and humidity of where you live. There are a number of ways to get a custom map, including through DNK Tuneworks who offer proprietary tuning maps that are designed exactly to fit your specific riding style and setup. 

One easily accessible source for preset maps is from Triumph itself. A Triumph dealership will be able to provide you with preset maps that have been designed for their stock Triumphs fitted with their Genuine Accessories exhausts. They have four maps that they can download to your bike:

- Stock (every Triumph starts with this)

- Triumph Off Road (TOR)

- Arrow 2-1

- Arrow 2-2

We’ve tested the Arrow 2-1 and Arrow 2-2 maps with our products and have listed which ones work best for different setups below in our tuning guide table. These tunes are considered proprietary for their Triumph exhausts so they are not specifically designed for use with other exhausts (like ours), but they will make your bike run better than if you run a stock tune with British Customs intake or exhaust modifications.

Although the mentioned Triumph tunes work,  we highly recommend using a third-party tuning software and purchasing customized maps from tuners like DNK Tuneworks, Triumph Twin Power (TTP), or installing a Power Commander and having your bike dyno tuned. 


For 2008-2017 Air Cooled Fuel Injected Triumphs with BC Slip-on Exhausts, Full Systems, and British Customs Performance Packages. We’ve listed the Triumph Preset maps that have been tested to work with our exhausts. There are other preset maps available on the market that also work, but we have not tested them ourselves. So we’re listing the Triumph maps as a tested option to use if you don’t want a custom tune.

For setups where the preset Triumph maps are not adequate, we’ve marked them as needing a custom tune.

* Disclaimer: these maps have been tested and will work, but for best performance a custom tune will give you the absolute most out of your bike


In 2016, Triumph redesigned the Triumph Modern Classic Line from the ground up. In addition to adding throttle by wire, ABS, and traction control, the fuel injection system was upgraded to an open-loop system with wideband oxygen sensors that provide even more detailed feedback to the bike than previously, allowing the bike to not only adapt to environment and altitude but to subtle upgrades to the exhaust as well. This system is smarter than its predecessor and can essentially remap itself for smaller bike upgrades like slip-ons.

To protect the bike from damaging itself however, there are minimum and maximum adjustment levels built into the system. This puts limits on the amount the ECU can tune and adjust itself to for safety reasons and to protect the bike and rider.   

Some British Customs upgrades fall outside the limit of what the ECU can adjust itself to and will therefore need a remap. Other mods we offer fall right on the edge of what the bike is able to adjust itself to, so remapping is optional, but is always a good idea if a rider wants to truly optimize their bike and have it running its best. 

Since the Liquid Cooled Triumph models are able to adjust themselves to an extent, there are fewer British Customs upgrades that a Liquid Cooled Triumph will need a remap for. 

Example of subtle BC upgrades: (components that it can adjust to itself)

- Intake (High Flow Replacement Air Filter, Snorkel)

- Exhaust (Slip-On Exhaust)

More significant upgrades require you to adjust the bike’s tune. The ECU will adapt as much as it can, but these upgrades will fall on the very end of the spectrum of what it can adjust for, so it’s best to get a custom tune. 

Example of significant BC upgrades: (components that the ECU cannot adjust to itself and will need a remap for):

- Intake (Air Box Removal Kit)

- Exhaust (Slip-on + Cat Delete,  2-1 Full Systems, 2-2 Full Systems)

Triumph does not offer map downloads for the new Liquid Cooled HT Parallel Twin, since it is able to self adjust to their accessories.

If your upgrades are significant and outside of the range of what the ECU is capable of adjusting to, you’ll have to use a custom map to retune your motorcycle. 

A customized map is bespoke to your specific bike and modifications, fully optimized for your specific set up and riding needs. The most popular providers of custom Triumph tunes for liquid cooled Triumphs are DNK Tuneworks and Power Commander, who offer proprietary tuning maps that are designed exactly to fit your specific riding style and setup.

See the tuning chart below for reference.


For 2016+ Liquid Cooled Triumphs with British Customs Slip-On Exhausts, Full Systems, and British Customs Performance Packages (Slip-On Exhaust or Full System + X/H-Pipe + Air Filter).

Modifying the slip on pipes alone won't require a tune but adding in an X-Pipe, H-Pipe or even switching over to a full exhaust system will require a tune which we highly recommend to get the most out of your bike.

Tuning your Liquid Cooled triumph with DNK Tuneworks

Watch the video below to learn more from DNK Tuneworks about the different ways they can custom tune your bike