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Carburettor vs Fuel Injection – the Debate Goes on

motorcycle air filterIn the motorcycle world, the battle between carburettors and fuel injection roars on.

While most beginners may not give either option a second thought (they’re likely more interested in the price, power and brand of their bike), experienced riders often put one or the other at the top of the list when looking at motorcycles for sale.

But how many of you actually know the difference? And, more importantly, does it really matter?

The short answer? Yes, it does matter – and here’s why…

Advantages of a carburetted system

A carburettor is dependent upon the velocity of air entering the venturi to create a good air/fuel mix to feed the engine, and serves to maintain the fuel circuits which pump the petrol – and although the majority of current high-performance bikes have switched to fuel injection, there are still plenty of motorcycles fitted with carburetted engines.

Surprisingly, you’re likely to find most mechanics have less experience with fuel-injection systems. And for those used to fixing their own mechanical problems, a carburettor is likely to cause fewer problems as they’re simpler to repair and maintain. Critics tend to condemn the carburettor for its relatively poor performance at low temperatures as the choke system used to get the cold engine up and running.

Condensation causes cold fuel to stick to the walls of the cylinder, which means the mixture is too thin for the engine to start. The choke pumps additional fuel into the engine to make up for the fuel stuck to the cylinder walls – but once the motorcycle engine is warmed up, condensation isn’t a problem and the need for the choke is gone.

motorcycle air filterBenefits of a fuel injection system

Nowadays, most riders will turn the key in the ignition, jump on and speed off without a second thought – and that’s because a fuel injected engine makes cold starts much easier. Technically, though, the mechanics are far more complex.

First of all, there’s a fuel pump inside the tank, an electronic engine controller, and an assortment of sensors. The fuel injected system is controlled by a computerised fuel delivery system, while the ECU takes information from various sensors and determines how much fuel the engine receives based on this data. Other sensors deal with RPM, engine temperature, throttle position, and the crankshaft position.

Additionally, the fuel required for each RPM and engine load condition is located in the fuel map within the ECU. Once the amount of fuel is identified, the ECU will adjust the fuel mixture for the engine and air intake temperatures.

Crucially, most carburettor problems can be fixed easily at the side of the road with an assortment of basic tools. An electronic fuel injection system, though, if it goes wrong, will usually require a new part – and that’s going to cost you…

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Mark Cuthill is fanatical about motorcycles and treats his ride like one of the family. He has contributed this guest post on behalf of Motorcycle News, the number one choice when you’re looking for a new or used motorcycle.

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YouMotorcycle is a lifestyle motorcycle blog to be appreciated by those who see motorcycling as a lifestyle and not simply a hobby, sport, or method of transportation. Most of the posts on the site are written by past and present motorcycle industry staff. We remain fiercely independent, innovative, and unconventional. Our goal is to encourage more people to enjoy the world's greatest outdoor sport by helping new riders get started and inspiring current riders to get out more. We motorcycle, do You?

2 comments

  1. Getting to the bottom of this article I caught myself going “whew! That was a close one, I almost ditched my carbs for some throttle bodies!” And about two seconds later I slapped myself. You can paint the picture of fuel injection systems as these mysterious devices for people who don’t own a wrench and have deep pockets, but the reality is they’re not that hard to understand or work on. And the whole argument of being able to work on one on the side of the road is null and void. I don’t know what you carry with you on your bike that allows you to troubleshoot your carb on the side of the road, but the whole benefit of fuel injection systems is NOT having to work on them. When a sensor goes bad sure they can be a little pricey, but not as pricey as that carb that after a rebuild kit and carb soak it still doesn’t run right so you just buy a new rebuilt carb because you’re tired of it.

  2. Carbs are fine for those who like old-school. For those of us who want a modern machine to rival a car, fuel-injection all the way! I would add my bike also has liquid cooling and a 6-speed transmission. I wish it had throttle-by-wire too so it had cruise-control too. Oh ABS and TCS and TPMS are also must haves.

What do you think?