What is a Motorcycle Engine?

Lori Kilchermann
Lori Kilchermann
Cross country motorcycles usually have smaller, lighter engines than street models.
Cross country motorcycles usually have smaller, lighter engines than street models.

A motorcycle engine is one that powers a motorcycle, and often contains one to six cylinders and can be fuel injected, carbureted and even turbo charged. Early motorcycle engine design relied on two-stroke combustion and lubrication, but most modern versions are of the four-stroke design. Most motorcycle engine design has the transmission engineered into the engine casing, and the two components function as a single design.

Racing motorcycles typically have engines that can handle prolonged high RPMs.
Racing motorcycles typically have engines that can handle prolonged high RPMs.

The motorcycle engine is typically designed to make its peak horsepower at high engine revolutions per minute, or RPMs. The typical motorcycle is able to comfortably operate at 6,000 to 8,000 RPMs without damage. Some of the Japanese cafe style motorcycles are able to withstand prolonged operation at 10,000 RPMs and above. There are even some specially designed drag racing motorcycles that are able to operate safely far beyond that.

Harley Davidson has an air-cooled engine.
Harley Davidson has an air-cooled engine.

The motorcycle engine does not differ much from the engine found in the average automobile, but it is typically built on a smaller scale. The basic functions of fuel, fire and compression exist in the motorcycle and it is prone to the same types of mechanical problems as the automobile. Overheating and fuel delivery problems are the most common in the motorcycle engine. Typically, poor maintenance is behind most problems.

While the motorcycle is liquid cooled in most cases, it does have some very high-tech features that have not yet found a home in the automobile engine. Exotic alloys used in engine production as well as space-age design in the power plants help to create ultra fast and quick accelerating machines. Some experimental models have included such features as oval shaped pistons in the engine design, driving the cost of the motorcycle into the super-car league and beyond.

In the United States, Harley Davidson has elected to stay with an air-cooled engine design very similar to its original early 1900s-style motorcycles. The Harley Davidson V-twin, air-cooled motorcycle engine is a stand-alone engine. The engine is separated from the transmission in this design and is connected to the transmission via a drive chain or belt called a primary drive. The transmission can be a four- to six-speed unit and the final drive to the rear tire can be either a roller chain or a cogged belt. Modern technology has found its way into the Harley Davidson design studios, and it is offering a liquid cooled, shaft drive version, in its line up.

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    • Cross country motorcycles usually have smaller, lighter engines than street models.
      By: Svetoslav Sokolov
      Cross country motorcycles usually have smaller, lighter engines than street models.
    • Racing motorcycles typically have engines that can handle prolonged high RPMs.
      By: Lario Tus
      Racing motorcycles typically have engines that can handle prolonged high RPMs.
    • Harley Davidson has an air-cooled engine.
      By: Craig Hosterman
      Harley Davidson has an air-cooled engine.