Wheels

Motorcycle wheels are generally made of aluminum or steel rims with spokes, although some models that were introduced in the 1970s can offer cast wheels. Cast wheels allow the bikes to use tubeless tires, which unlike traditional pneumatic tires, don't have an inner tube to hold the compressed air. Instead, the air is held between the rim and the tire, relying on a seal that forms between rim and tire to maintain the internal air pressure.
A tire is made up of several different components. The Bead Bundle, The Body, The Belts, The Sidewall, The Tread .
All of these components are assembled in the tire-building machine. This machine ensures that all of the components are in the correct location and then forms the tire into a shape and size fairly close to its finished dimensions.

Harley-Davidson Engines

Harley-Davidson Engin seems to work on a completely different clock, with new engine designs appearing every 15 years or so. Between the years 1936 and 2003, engine designs released by Harley represented a constant tweaking of the same basic V-twin, 45-degree, air-cooled engine design.  In 2001, Harley released its first truly new design in a commercial motorcycle, yet it was still a V-twin. If you ignore the first few years of the company's history as a period of experimentation, there really have been only seven major engine revisions during the company's 100 year existence:

Knucklehead engines 1936-1947

Panhead engines 1948-1965

Flathead engines 1909-1936

Shovelhead engines 1966-1983

Evolution engines 1983-1999

Twin Cam 88 engines 1999-Present

Brakes

The front and rear wheels on a motorcycle each have a brake.

 The rider activates the front brake with a hand lever on the right grip, the rear brake with the right foot pedal. Drum brakes (Shoes press against a spinning surface) were common until the 1970s, but most motorcycles today rely on the superior performance of disc brakes.  Disc brakes consist of a steel braking disc, which is connected to the wheel and sandwiched between brake pads. When the rider operates one of the brakes, hydraulic pressure, acting through the brake line, causes the brake pads to squeeze against the disc on both sides. Friction causes the disc and the attached wheel to slow down or stop. Brake pads must be replaced periodically because the pad surfaces wear away after repeated use.

Gearset

A gearset is a set of gears that enable a rider to move from a complete stop to a cruising speed.  Typical transmissions on motorcycles have four to six gears, although small bikes may have as few as two.  The gears are engaged by shifting a lever, which moves shifting forks inside the transmission.

Transmission

A motorcycle engine can create an enormous amount of power, which must be delivered to the wheels of the vehicle in a controllable way. The motorcycle transmission delivers power to the rear wheel through a series of structures that include the gearset, the clutch and the drive system.

Clutch

The job of a clutch is to engage and disengage power from the engine crankshaft to the transmission. Without the clutch, the only way to stop the wheels from turning would be to turn off the engine -- an impractical solution in any kind of motorized vehicle. The clutch is a series of spring-loaded plates that, when pressed together, connect the transmission to the crankshaft. When a rider wants to shift gears, he uses the clutch to disconnect the transmission from the crankshaft. Once the new gear is selected, he uses the clutch to reestablish the connection.

Changing Gears

Early motorcycle clutches were operated by a foot pedal in the same way that automobile drivers use clutches. This was awkward and dangerous because it required that the rider's left foot be off the ground when the bike came to complete stop (at an intersection, for instance). British designers solved this problem with a hand-operated clutch. Today, hand-operated clutches and foot-operated shifters are standard on all models.

Cylinders

Motorcycle engines can have between one and six cylinders. For years, the V-twin design was the engine of choice for motorcycle engineers in America, Europe and Japan. The V-twin gets its name from the fact that the two cylinders form a V shape, such as the classic Harley-Davidson V-twin shown below. Notice the 45-degree angle in the Harley-Davidson V-twin -- other manufacturers may vary this angle to reduce vibration.The V-twin is just one way to accommodate two cylinders. When the cylinders are oriented so that the pistons oppose each other, the result is an opposed-twin design. Parallel-twin engines have their pistons placed side by side in an upright position. the most popular design is the four-cylinder, which runs more smoothly and at higher revolutions per minute (rpms) than a comparable twin. The four cylinders can be placed in a row, or they can be arranged in a V-shape configuration, with two cylinders on each side of the V.

Capacity

The size of the combustion chamber in a motorcycle engine is directly related to its power output. The upper limit is about 1500 cubic centimeters (cc), while the lower limit is about 50 cc. The latter engines are usually found on small motorcycles (mopeds) that offer 100-miles-to-the-gallon fuel economy but can only reach top speeds of 30 to 35 miles per hour.

The Horn