General Knowledge of Motorcycles

Motorcycles, which usually are heavier and more powerful vehicles than mopeds or motor scooters, have diverged very sharply into distinctly different groups. One important distinction, made according to intended use, is that all motorcycles are either highway or off-road types. Some of the off-road types are called on-road–off-road vehicles. Such motorcycles are intended for off-road operation but may have a secondary highway capability. Others either are pure racing machines or have only the rudimentary lighting equipment needed to make them eligible for endurance, or regularity, events. Mostly single-cylinder engines are used in off-road motorcycles, and piston displacements are mostly in the range from 125cc to 400cc.

Street or highway motorcycles are enormously diverse in size, weight, price, and performance. Some are machines that could be described as mopeds without pedals. Such small, low-performance motorcycles have only limited popularity in the United States, where the automobile is the principal mode of transportation, and motorized two-wheelers are regarded as sporting equipment.

For various reasons, highway motorcycles with engine displacements around 400cc are most popular. Motorcyclists think of these models as middleweights that have only moderate performance. Their actual weight usually is about 450 pounds (204 kg), and they combine a top speed of about 90 miles (145 km) per hour with a standing-start quarter-mile (0.4 km) time of just under 15 seconds. The speed at the end of a quarter mile of acceleration is well above 80 miles (130 km) per hour. In this respect, middleweight motorcycles are the equal of automobiles that generally are considered "performance" vehicles.

At the upper extreme, motorcycles are much faster than automobiles. The machines motorcyclists call superbikes have top speeds very near 135 miles (217 km) per hour. They perform a quarter-mile acceleration to 115 miles (185 km) per hour in about 12 seconds.

Fuel economy in motorcycles does not suffer greatly as performance rises. At a steady 55 miles (88 km) per hour, motorcycles with engine sizes from 250cc to 1,000cc will all use fuel at the rate of 45 to 50 miles (72–80 km) per gallon.