Harley-Davidson, Inc. (H-D), or Harley, is an American motorcycle manufacturer founded in 1903. As one of two major American motorcycle manufacturers to survive the Great Depression, the company has survived numerous ownership arrangements, subsidiary arrangements, periods of poor economic health and product quality, as well as intense global competition to become one of the world's largest motorcycle manufacturers and an iconic brand widely known for its loyal following, with owner clubs and events worldwide as well as a company sponsored brand-focused museum. Harley-Davidson traditionally marketed heavyweight, air-cooled cruiser motorcycles with engine displacements greater than 700 cm³ and has broadened its offerings to include its more contemporary VRSC (2002) and middle-weight Street (2015) platforms.
In 1901, 20-year-old William S. Harley drew up plans for a small engine with a displacement of 7.07 cubic inches (116 cc³) and four-inch (102 mm) flywheels. The engine was designed for use in a regular pedal-bicycle frame. Over the next two years, Harley and his childhood friend Arthur Davidson worked on their motor-bicycle using the northside Milwaukee machine shop at the home of their friend, Henry Melk. It was finished in 1903 with the help of Arthur's brother, Walter Davidson. Upon testing their power-cycle, Harley and the Davidson brothers found it unable to climb the hills around Milwaukee without pedal assistance. They quickly wrote off their first motor-bicycle as a valuable learning experiment.
The first "real" Harley-Davidson motorcycle had a bigger engine of 24.74 cubic inches (405 cc³) with 9.75 inches (25 cm) flywheels weighing 28 lb (13 kg). The machine's advanced loop-frame pattern was similar to the 1903 Milwaukee Merkel motorcycle. The bigger engine and loop-frame design took it out of the motorized bicycle category and marked the path to future motorcycle designs. The boys also received help with their bigger engine from outboard motor pioneer Ole Evinrude, who was then building gas engines of his own design for automotive use on Milwaukee's Lake Street. The prototype of the new loop-frame Harley-Davidson was assembled in a 10 ft × 15 ft (3.0 m × 4.6 m) shed in the Davidson family backyard.
Harley-Davidson launched a line of bicycles in 1917 in hopes of recruiting customers for its motorcycles. Besides the traditional diamond frame men's bicycle, models included a step-through frame 3-18 "Ladies Standard" and a 5-17 "Boy Scout" for youth. The effort was discontinued in 1923 because of disappointing sales. The bicycles were built for Harley-Davidson in Dayton, Ohio, by the Davis Machine Company from 1917 to 1921, when Davis stopped manufacturing bicycles.
Harley-Davidson's association with sportbike manufacturer Buell Motorcycle Company began in 1987 when they supplied Buell with fifty surplus XR1000 engines. Buell continued to buy engines from Harley-Davidson until 1993, when Harley-Davidson bought 49 percent of the Buell Motorcycle Company. Harley-Davidson increased its share in Buell to ninety-eight percent in 1998, and to complete ownership in 2003. In an attempt to attract newcomers to motorcycling in general and to Harley-Davidson in particular, Buell developed a low-cost, low-maintenance motorcycle. The resulting single-cylinder Buell Blast was introduced in 2000, and was made through 2009, which, according to Buell, was to be the final year of production.
The classic Harley-Davidson engines are V-twin engines, with a 45° angle between the cylinders. The crankshaft has a single pin, and both pistons are connected to this pin through their connecting rods. This 45° angle is covered under several United States patents and is an engineering tradeoff that allows a large, high-torque engine in a relatively small space. It causes the cylinders to fire at uneven intervals and produces the choppy "potato-potato" sound so strongly linked to the Harley-Davidson brand. Harley-Davidson has used various ignition systems throughout its history – be it the early points and condenser system, magneto ignition system used on some 1958 to 1969 Sportsters, early electronic with centrifugal mechanical advance weights, or the late electronic with transistorized ignition control module, more familiarly known as the black box or the brain.
