If Carburetors and Fuel Injection Had a Fistfight, Who Would Win?

A quick look at the pros and cons of carbs and EFI.

Carburetors and fuel injection both have the same job, which is to wrangle fuel and air in the right ratio to yield proper combustion.

Carburetors are your old-school, analog option, and they're what all bikes relied on until electronic fuel injection began to appear in the '80s. Nowadays, the vast majority of bikes have EFI, though plenty of smaller motorcycles and scooters still use carbs to help keep them affordable.

Carburetors have stood the test of time because they get the job done and they’re cheap to make and straightforward to set up. They may look complicated, but carburetors are pretty simple devices. They just rely on intake vacuum, created by the piston moving down in the cylinder, to draw fuel up out of the float bowl and into the combustion chamber. That’s a super-simplified explanation of how they work, but the point is that a carb’s function is strictly mechanical. That’s both a blessing and a curse, though, because while carbs don’t need electricity or separate systems to do their job, their function, and thus the running of your motorcycle, is affected by things like air and engine temperature, elevation, and other outside factors.

Electronic fuel injection, on the other hand, doesn’t care if it’s hot or cold out or if you’re at sea level or riding over a mountain pass at 10,000 feet. A fuel-injected bike’s throttle body may look less complicated than a carburetor, but EFI has a lot going on and there are separate systems with lots of circuit boards and sensors helping EFI do its job. The main difference is that instead of reacting to pressure changes like a carburetor does, EFI makes its own pressure with a fuel pump so it can deliver fuel into the engine whenever it wants.

With all those sophisticated components, fuel injection is a far more precise means of feeding the engine fuel, so the motorcycle runs better. There's no choke lever to mess with on cold mornings or leaking float bowls or petcocks or gummed-up jets. The truth is modern EFI is extremely reliable, so you're unlikely to ever have an issue with your fuel system. That being said, if something does go wrong, the odds of your being able to make a roadside repair are slim, and replacement parts, like a new fuel pump or throttle position sensor, are expensive. The part you can service yourself, the injector itself, can be cleaned using this tool from Motion Pro.

Carburetor parts on the other hand, are pretty affordable, and carbs are easy enough to work on at home with basic tools. Unfortunately, you most definitely will end up working on them. Carburetors need to be serviced and maintained, and while the work itself isn’t usually that hard, it’s time-consuming and inconvenient. That inconvenience, or more appropriately the incredible convenience and reliable operation of fuel injection, is part of the reason carburetors are becoming so rare.

What’s really killed carbs, though, are environmental concerns. EFI is dynamic and can stick to a very narrow air-fuel-ratio range to help improve fuel efficiency and reduce tailpipe emissions, whereas carbs, with their fixed jets, just aren’t that precise or adaptable. That means more unburned gas going out the exhaust and more soot that will kill a catalytic converter. And even when they’re parked, carbureted bikes waft gas vapors from the open vents on their float bowls and gas tanks. And with today’s strict emissions requirements, that sorta stuff just doesn’t fly, so manufacturers have switched to fuel injection.