Automobiles are a popular mode of transportation in the United States and other countries. They are convenient and economical. In the beginning, they were considered a luxury. However, with mass production, they became more affordable. Manufacturing techniques were modified to lower the cost. This meant that more people could afford automobiles.
The Environmental Protection Agency (EPA) first regulated motorcycle hydrocarbon emissions in 1980, requiring that new motorcycles emit no more than 5.0 grams of carbon monoxide and nitric oxides per kilometer. In 2006, the EU and California adopted stricter limits for hydrocarbons and nitric oxides. New motorcycles had to meet emissions limits of 1.4 grams of hydrocarbons and nitric oxides per kilometer by 2016. In 2010, motorcycle emissions were limited to 0.8 grams of hydrocarbons and nitric oxides per kilometer.
A motorcycle’s transmission system consists of four to six gears, although some small motorcycles have two-speed transmissions. Power is transferred to the wheels through a chain, belt, or shaft. The clutch and throttle controls are located near the handgrip and a foot pedal engages the rear brake. Historically, motorcycles had kick starters, but now many have electric push-button starters.
While motorcycles and automobiles are often categorized together, motorcycles do not fit into the definition of an automobile. Motorcycles, for example, do not have side-cars, are three-wheeled vehicles with four wheels and are not intended to transport cargo. Some court cases have ruled motorcycles to not be automobiles.