With gas prices rising higher and higher everyday, many people turned to alternate forms of transportation. One of the most popular forms of transportation is motorcycles. These vehicles can save a lot of money at the pump. Sports involving motorcycles are also becoming more and more popular everyday. Motocross is the second most popular motorsport in America behind NASCAR. This growth of the motorcycle industry got me curious about these amazing machines and how they work. The first motorcycles were made in America.
In 1867, American, Sylvester Howard Roper invented a steam-engine motorcycle that was powered by coal called the Roper Steam Velocipede. German, Gottlieb Daimler invented the first gasoline-powered motorcycle in 1885. This is considered by most to be the first true motorcycle. Daimler used a four-stroke engine that was invented by Nicolaus August Otto. It was the first four-stroke internal combustion engine (Tank). There are two main types of engines used in the motorcycle industry. They are two-stroke engines and four-stroke engines.
The primary difference between the two is in a two-stroke engine power is made every revolution of the engine. Four-stroke engines make power once every two revolutions. A two-stroke engine will make more power because of the way it operates. However, the disadvantage to the two-stroke engine is that it burns gasoline as well as oil. This is not only more harmful to the environment but it is not best suited for most motorcycles. Two-stroke engines are used in motocross and some other motorsports where weight and power are more important, but advancements in four-stroke engines have made two-stroke engines obsolete (House).
In a two-stroke engine, a piston moves up and down in a cylinder and is responsible for compressing an air/fuel mixture by moving upward in the cylinder. The piston then moves back down around the explosion of the ignited mixture. The piston then transfers the energy of the explosion to the connection rod. The power is then transferred to the crankshaft. The crankshaft is the part of the engine that is responsible for converting the motion of the piston to a force that is used to turn the rear wheel of the motorcycle. This process then repeats many times (House).
In a four-stroke engine there are four cycles, or strokes, that the motor goes through to make power. First is the intake stroke, an air/fuel mixture is moves into the cylinder through the piston moving in a downward motion. This creates a vacuum which draws in the mixture. The second cycle is the compression stroke. The piston moves up into the cylinder compressing the air/fuel mixture. The third stroke is the combustion stroke. The compressed air/fuel mixture is ignited by the sparkplug creating an explosion that forces the piston downward.
The fourth and final cycle is the exhaust stroke. The piston moves upward in the cylinder and releases the burnt gasses. The whole process is then repeated (House). Four-stroke engines are controlled by valves which open or close depending on the cycle the engine is on. Valve opening and closing sequences are controlled by the camshaft. The camshaft is one of the most important components of the four-stroke engine. Camshafts are similar to the crankshafts. The camshaft turns a rotating motion into an up and down motion. This motion is used to push the valves open.
In some engines the camshaft sits above the valves. Other engines have two camshafts that sit above the valves. In older engines and still in most V-Twin engines the camshaft is positioned down by the crank in the lower part of the motor. The valves are usually positioned at the top of the motor, thus more parts are required to open them. In the case of a non-overhead camshaft, lifters and pushrods are used with rocker arms to open the valves. The lifters slide along the lobes of the camshaft and raise and lower with the lobes.
Then the lifters push on the pushrods which push on one side of a rocker arm. The other side of the rocker arm then pushes down on the valve to open it. Some overhead camshaft designs use rocker arms to open the valves as well. Instead of the lifters and pushrods, the rocker arm rides along the camshaft lobe and the other end still opens the valve. In other overhead camshaft designs the cam lobe pushes on the valve itself (House). Four-stroke engines are more commonly used than two-stokes. They are used in most motorcycles that are used for transportation, such as Harley Davidson motorcycles.
These engines are becoming even more popular than they once were. There have been many advancements in the four-stroke engine that have made them capable to do jobs they were once unable to do. These engines are now used more commonly in motocross competition and off-road use, the only portion of the motorcycling industry that mostly used the two-stroke engine (Bennett). This is largely due to the fact that fuel economy and environmental awareness are very important issues in the world right now (Total
Motorcycle). Besides the mechanics, there are many other differences between two-stroke engines and four-stroke engines (Total Motorcycle). Both engines use gasoline for fuel, but two-stroke engines require a mixture of gasoline and oil. This is needed to lubricate the inner parts of the engine, while four-stroke engines have a completely separate oiling system that lubricates the engine. The mixture of oil and gas makes these engines more harmful to the environment and produces more harmful emissions.
Four-stroke engines also use less gasoline than two-stroke engines. Therefore, they are more efficient and create less pollution (House). Motorcycles have come a long way since Sylvester Howard Roper invented his steam-powered Velocipede. They have become a large part of American culture. They are now part of popular motorsports world. Motorcycles have become some of the most popular and efficient vehicles in the world. They have changed greatly, and will only become more advanced as new technology is discovered.
