Carburetor vs Fuel Injection Motorcycles: 2021 Complete Comparison Guide

Troy
| Last Updated: March 14, 2021

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Granted, fuel injection and carburetors get the job done when it comes to wrangling air and fuel in the ideal ratio to yield excellent combustion. However, it’s no secret that fuel-injected motorcycles are quickly dominating their carbureted counterparts that ruled the roost up until the start of the new millennium. It wasn’t until the 1980s that fuel injection made its way on a street-going bike.

As it stands, most premium motorcycles are armed with a fuel injection (FI) system. While others swear by the serviceability, tune-ability, and reliability of carburetors, newer riders believe that fuel injection takes the crown in more ways than one.

If you’re curious as to how these systems work along with their respective vices and virtues, then you’ve come to the right place. Buckle up as we delve into the carburetor vs. fuel injection motorcycle battle.

Photo Credit: MotorcycleHabit.com

What Is a Carburetor Motorcycle and How Does a Carburetor Work?

To gain more insight, we’ll start by discussing what a motorcycle carburetor is. In a nutshell, it’s a series of carburetors that have the uncanny ability to create a combustible blend of air and gasoline that will power the engine of a motorcycle and create the driving required to propel it forward.

Carburetors have been improved and modernized over the years. Nonetheless, the fundamental premise of combining air and fuel remains constant. 

Carburetors have stood the test of time because they’re not only cheap and a breeze to set up, but they also get the job done. Carburetors may look complicated; however, these simple devices depend on the intake vacuum that stems from the piston moving down in the cylinder to extract fuel from the float bowl and right into the combustion chamber.

While this is an incredibly simplified explanation of how they function, the point is, how a carburetor works are solely mechanical, which can be both a blessing and a curse.

Carburetors don’t require independent systems or electricity to get the job done. However, the running of a motorcycle and its function are impacted by external factors ranging from elevation, and air, to engine temperature.

Photo Credit: Fix.com

What Components Make Up a Carburetor on a Motorcycle?

The components that make up a carburetor in a motorcycle are:

  • Throttle valve
  • Step-up/metering rod or power valve
  • Bowl
  • Choke
  • Adjustment screws
  • Air passage
  • Accelerator pump
  • Float chamber
  • Throttle linkage 

What Is a Fuel Injection Motorcycle and How Does Fuel Injection Work?

A fuel injection motorcycle contains a complex set of sensors and electronics. It relies on a fuel pump installed in the tank to deliver fine-grained control over fuel flow.

The fuel injection nozzle is inserted into the combustion chamber, after which the pressurized and atomized fuel that becomes a homogenous mist paves the way for clean and efficient combustion.

The fuel supply in a fuel injection motorcycle is regulated via an ECU or electric brain that continuously makes complex calculations at a significantly high frequency. As a result, it provides an excellent blend of fuel and air.

Factoring in a vast assortment of parameters ranging from the load, engine speed, and engine temperature to throttle position, the ECU guides the injectors to allow just the required amount of fuel with each intake stroke.

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In turn, it facilitates combustion of unmatched efficiency. With that being said, the efficacy of a fuel injection system is superior to carburetors.

What Components Make Up a Fuel Injection System on a Motorcycle?

A fuel injection system can be categorized into high-pressure and low-pressure sides. The high-pressure side consists of the following components.

  • Fuel injector nozzle
  • High pressure pump
  • Fuel injector
  • Accumulator 

The low-pressure components of a fuel injection system are:

  • Fuel filter
  • Fuel supply pump
  • Fuel tank 

Carburetor vs Fuel Injection Motorcycle Similarities and Differences

We will take a deeper look at the differences and similarities between the carburetor and fuel injection motorcycle.

Similarities

Let’s delve into the commonalities that fuel injection and carburetor motorcycles share.

Internal Combustion

The carburetor vs. fuel injection systems are found in internal combustion engines of motorcycles. For internal combustion engines to function properly, an explosion must occur within the engine to convert the energy needed to power the motorcycle.

The combination of air and fuel ignites a spark plug-in. It results in a minor explosion that gets the pistons in continuous up and down motions. It’s the energy produced by these pistons that turns the crankshaft and powers the bike.

Purpose

When comparing a carburetor vs. injection motorcycle, it’s essential to keep in mind that they both serve the same purpose of feeding air and fuel into the engine. The difference lies in the method by which they do so.

Differences

Here’s a breakdown of a few aspects that set fuel injection and carburetor motorcycles apart.

Performance

Carburetor motorcycles are solely mechanical and don’t depend on electronics. Therefore, the components that are susceptible to wear and tear will need replacement in the long run. They are usually tuned to function seamlessly on a narrow target rev range and call for periodic tuning and maintenance to prevent clogging.

Contrarily, fuel injection motorcycles have superior efficiency and can be fine-tuned for optimal engine functioning throughout the entire rev range. While an FI system heavily depends on its onboard electronics and needs auxiliary components such as sensors and a fuel pump to function, it delivers robust, foolproof, and maintenance-free operation.

Repairs

Contrary to a carburetor motorcycle that you can tweak and tune with a mere screwdriver, the fuel injection counterpart calls for technical know-how, computers, and unique software to fiddle with. In turn, this makes a carburetor advantageous for anyone who knows how to tinker with their bikes.

Cold Starts

At low temperatures, carbureted motorcycles require some time before they’re ready to hit the road. The choke system is used to start cold engines. Given that the fuel in a cold engine sticks to the cylinder walls as a result of condensation, the mixture is overly lean for the engine to start.

Cold starts are incredibly simpler in fuel-injected motorcycles. With no carburetor or choke adjustment, simply turn the key and hit the start button.

Price

Granted, fuel injection systems come with perks such as superior power, fuel efficiency, and little to no maintenance required. However, this comes at a substantially steeper price than carburetor motorcycles designed with affordability in mind.

Top Pick Between a Carburetor and Fuel Injection Motorcycle

Fuel injection motorcycles are the clear winner when it comes to the following.

Throttle Response

It’s no secret that most carburetor motorcycles have a slight lag that ushers in fairly slow throttle response. However, with the fuel injection counterpart, lagging is the least of your worries as it has a sharper throttle response.

Fuel Efficiency

Fuel injection motorcycles are more dynamic by delivering fuel in just the right amount and tweaking it according to various parameters, resulting in better fuel efficiency and lower tailpipe emissions.

Carburetors, on the other hand, are unable to alter the fuel ratio to suit the current conditions of the engine. Therefore, there’s more unburned gas being emitted from the exhaust along with more soot that is detrimental to the environment. 

Conclusion

While new bikes are almost exclusively fuel-injected, many carbureted motorcycles, including ATVs and dirt bikes, are still used today. Therefore, after weighing the pros and cons of each, it ultimately boils down to your preference. 

People Also Ask

Let’s explore the answers to a few of the most frequently asked questions regarding the carburetor vs fuel injection motorcycle debate. 

Can You Replace a Carburetor With Fuel Injection?

Yes! The cost of upgrading your motorcycle from a carburetor to a fuel injection system will set back anywhere between $2000 and $3000, depending on the capabilities. 

Photo Credit: GearPatrol.com

How Do I Convert My Motorcycle Carburetor to Fuel Injection?

It’s a straightforward process that entails following the instructions below.

  1. Remove the rider’s seat and disconnect all the battery cables

  2. Disconnect the fuel lines and throttle linkages at the carburetors

  3. Find the stock connector, remove it, and attach the new one from the fuel injection kit

  4. Install the oxygen sensor at the first cylinder on the engine

  5. Install the throttle position and air sensors onto the new fuel injection throttle bodies

  6. Mount the ECU computer to the universal bracket

  7. Attach the fuel pump to the mount where you removed the old pump

  8. Reattach the new throttle bodies and linkage via the provided keepers and clips 

When Was Fuel Injection Invented?

The concept of fuel injection came about in 1925 courtesy of a Swedish engineer known as Jonas Hesselman. 

How Can You Tell If a Harley Is Fuel-Injected?

The simplest way to know if it is fuel-injected is by turning on the main switch then toggling the engine kill switch. If you hear a whine that seems to be originating from the right side of the tank’s interior, it’s undoubtedly a fuel injection motorcycle. However, if it’s silent, then it’s carbureted. 

What Does EFI Mean?

It’s an acronym for an Electronic Fuel Injection system that injects fuel directly into the cylinder or manifold of an engine via electronic controls. 

What Does MPFI Mean?

As an acronym for Multi-Point Fuel Injection System, it injects fuel into the internal combustion engine via several points located on each cylinder's intake valve. It’s through this system that a precise quantity of fuel can be delivered at the right time. 

Do They Still Make Carburetor Motorcycles?

Nowadays, most motorcycles use an EFI system. However, a boatload of smaller scooters and bikes still use carburetors to maintain affordability. 

Are Carburetor Motorcycles Loud?

Most carburetor bikes make a gentle ‘ticking’ noise when they are idle as a result of the normal air pulsing in the intake system. They also produce a loud pop or bang sound when they are not getting sufficient fuel.

Troy

Hi, my name’s Troy. I started riding motorcycles with Clay mid-2020 and soaking up his vast knowledge of bikes. I have been writing for a few years and decided it was a good time to start writing about what I’m passionate about - motorcycles. No matter how bad your day is, a bike will always make you feel better, that’s my motto.