The 'Harley-Davidson' motorcycle company's humble beginnings can be traced back to a small wood barn in Milwaukee, Wisconsin, back in 1903. After designing a small gas engine for mounting on a bicycle frame, William S. Harley joined with brothers' Arthur and Walter Davidson to build their first motorcycle, the "Silent Grey Fellow."
The Silent Grey Fellow was an overnight sucess, and by the 1910s the original 1903 prototype for the Silent Grey Fellow was being used as a promotional mascot, having clocked over 100,000 miles. (1909 Model 5A ' Silent Grey Fellow' shown above)
Zoom: 1923 Harley-Davidson JDCA Board Track Racer
Harley Davidson Twins
In 1919, Harley Davidson introduced the Model W Sport-Twin. The Model W was powered by a horizontally opposed side-valve, twin cylinder engine. The engine and transmission were mounted in the same cases making this model the first Harley Davidson Twin with 'unit' engine construction.
1929 Harley-Davidson Model JDH
Harley sales began to slow during the early 1920s recession, and a Harley Davidson motorcycle was now more expensive than Ford's least-expensive automobile. In reaction to this, HD introduced small-displacement single-cylinder motorcycles that could compete with the European bikes. This decision was not well received by the public, and Harley Davidson abandoned the marketing strategy in the mid 20s.
1929 Model JDH 74 ci (1200cc) V-Twin Engine
In the late 1920s, Harley Davidson introduced the Model JH and JDH, advertising the JDH as the "fastest model ever," with a top speed of 85 to 100 mph. The Model JH had a 1000 cc (61 cubic-inch) engine, and the JDH had a 1200 cc (74 cubic-inch) version. The twin-cam engine had a 'peanut-shaped' timing gear cover which made the engine recognizable.
Harley Davidson Nomenclature
Nicknames were given for the physical characteristics of the engine, that readily identified the era in which a particular Harley was built, and its engine/cylinder-head design.
Harley-Davidson 'Flathead' Side Valve (1930 to 1956)
Harley Davidson's "Flathead," or "Side Valve" engine design dates back to the early 1920s. The name comes from the location of the upside-down valves that are located alongside the cylinder, with the valve ports entering a flat combustion chamber above the cylinder bore.
1936 Harley-Davidson Model R Flathead
The 1200cc 74ci Flathead Model V (aka "Seventy-Four") replaced the long-running F-Head in 1930. The Flathead design remained popular throughout to 1940s, and the Model WLA Flathead was used by the US military during WWII, labeling it as the "bike that won the war."
1948 Harley-Davidson Model WR
Toward the end of Flathead production in the late 1940s, the design was relegated to smaller displacement V-twins like 700cc to 750cc Models WR, and WHR, or the Model K. The las of the Flathead engines was used on the 1956 Model KH.
Harley-Davidson 'Knucklehead' (1936 to 1947)
1936 was the first year for the Model E, which was nicknamed as the "knucklehead" due to the knuckle shape of its engine valve covers. The Model E was a slowly gained popularity, but it was the distance record set by Fred Ham that put the knucklehead Model E into the history books.
1937 Harley-Davidson Model E Knucklehead
1937 Harley-Davidson EL 1000 Knucklehead
1940 Harley-Davidson EL 1000
1947 Harley-Davidson EL 1000
The last of the 'Knuckleheads' was produced by Harley-Davidson in 1947. The new versions of Harley's OHV engine were introduced in 1948, featuring chrome-plated valve covers that resembled upside-down cake pans. This was the beginning of Harley-Davidson's "Panhead" era.
HD EL 61ci 1000cc V-Twin Engine
Harley-Davidson 'Panhead' (1948 to 1966)
The 'Panhead' or "tin top" overhead valve engine was introduced in 1948, with a 1000 cc (61 cubic-inch), and 1200 cc (74 cubic-inch) version. 1948 also ushered in the ear of the 'telescoping front fork,' ending the long run of 'springer' fork assemblies.
Harley-Davidson KRTT 750 Racer (1952 to 1969)
Starting in 1952, Harley-Davidson built the first 'KR' series 'competition class' full-fairing and flat track racers. The KR's "Milwaukee racing iron" engine was a 744cc side-valve flathead V-twin that produced around 30 horsepower. The KR with its 4-speed transmission was capable of a top speed of around 80 mph.
1959 Harley-Davidson KR Flat Tracker
Built as a replacement for Harley-Davidson's aging WR racing line, the KR would be a dominant force in dirt track and road-racing competition for almost 17 years. The KR took nearly every AMA Grand National Championship from 1954 to 1962.
1969 Harley-Davidson KRTT 750 Racer
By the late 1960s, the KRTT was capable of a 150 mph top speed, with around 50 bhp. From 1953 to 1969, the KR and KRTT delivered 13 victories at Daytona, making it one of the company's most successful road racing bikes. As the British competition started to gain an unbeatable foothold in the late 60s, HD decided to discontinue the KRTT in 1969.
Harley-Davidson 'Shovelhead' (1966 to 1984)
coming soon
Back To: Harley Davidson Two-Strokes - 1948 to 1974
Harley-Davidson Links
The A-Z of Harley-Davidson
Harley-Davidson Racing History
1952 - 1970 Harley Davidson KRTT 750
Classic Harley Twins
100 Years of Harley Davidson
Harley-Davidson Century
Harley-Davidson Aermacchi ERS Sprint CR/CRTT
Aermacchi Restoration & History
Aermacchi Models
Back To: Vintage Motorcycle Photos
