Sports Cycle

Induction Systems : Carburetors vs Fuel-Injection

Since Gottlieb Daimler constructed the first gasoline-powered motorcycle back in 1885, motorcycles have had carburetors - complex devices that mix gasoline and air into the fuel charge squirted into the combustion chamber. Carburetors, or carbs, as they are usually called, rely on their shape to create the vacuum pressure that provides the energy for this squirt. Although modern carbs are remarkably efficient devices, they share many similarities with the crude device old Gottlieb bolted onto his half-horsepower engine way back when.

Today, most motorcycles have one carburetor for each cylinder, with a few exceptions. The carburetor’s century-long supremacy as the ultimate form of motorcycle induction system has been challenged in the last decade by fuel injection. Fuel injection refers to a system that forces the fuel charge into the combustion chamber with an electronic or mechanical pump of some sort.


The first reliable motorcycle fuel-injection system appeared on BMW’s first four-cylinder motorcycle, the K100 of 1984. Now every engine BMW builds sports fuel injection.

Other makers are jumping on the fuel-injection bandwagon, too. Ducati introduced its first production fuel-injected bike in 1988, the 851 Superbike. Suzuki now offers a large numbers of models with fuel injection. Honda recently introduced its new, Fuel-injected CBR650F, and even Harley-Davidson offers fuel injection on some models.

With the universal acceptance of fuel injection in the automotive world, it might seem odd that motorcycles have been slower to adopt the technology. Fuel injection offers certain benefits, such as greater control over the ratio of the fuel charge and less dependence on atmospheric conditions, but for some reason, motorcycle fuel-injection systems have so far provided less than satisfactory results. The biggest problem seems to be a surging in the engine, which makes it difficult to maintain a steady RPM level.

Such jerky power delivery on a sportbike can be dangerous, since these bikes are often ridden close to their handling limits. When you’re riding right on the edge, an unexpected surge in power while heeled over in a hard corner can lead to a trip to the emergency room.

The problems with fuel-injection systems on motorcycles seem to involve cost and size. Automotive systems incorporate many computerized controls not found on systems used on motorcycles. However, automotive systems tend to be too large to work in the compact space available on a motorcycle, and they are also quite expensive. Although some bikes still suffer driveability problems with fuel injection systems, more and more bikes are using such systems, most with no ill effects at all. Modern technology has finally made fuel injection a viable option on motorcycles.