Harley-Davidson motorcycle engines.
V-twin in a HD Road King.
The classic Harley-Davidson motorcycle engine is a two-cylinder, V-twin engine with the pistons mounted in a 45° "V". The crankshaft has a single pin, and both pistons are connected to this pin through their connecting rods.
This design causes the pistons to fire at uneven intervals, the consequence of an engineering tradeoff to create a large, powerful engine in a small space. This design choice is entirely vestigial from an engineering standpoint, but has been sustained because of the strong connection between the distinctive sound and the Harley-Davidson motorcycle brand. This motorcycle engine design, which is covered under several United States patents, gives the Harley-Davidson V-twin its unique choppy "potato-potato" sound. To simplify the engine and reduce costs, the V-twin ignition was designed to operate with a single set of points and no distributor, which is known as a dual fire ignition system, causing both spark plugs to fire regardless of which cylinder was on its compression stroke, with the other spark plug firing on its cylinder's exhaust stroke, effectively "wasting a spark." The exhaust note is basically a throaty growling sound with some popping.
The 45 degree design of the engine thus creates a plug firing sequencing as such: The first cylinder fires, the second (rear) cylinder fires 315° later, then there is a 405° gap until the first cylinder fires again, giving the engine its unique sound.
Harley Davidson motorcycle company has used various ignition systems throughout its history - be it the early points/condenser system, (Big Twin up to 1978 and Sportsters 1970 to 1978), magneto ignition system used on 1958 to 1969 Sportster motorcycle, early electronic with centrifugal mechanical advance weights, (all motorcycle models from 1978 and a half to 1979), or the late electronic with transistorized ignition control module, more familiarly known as the black box or the brain, (all motorcycle models 1980 to present).
With the implementation of Electronic Fuel Injection (EFI), the Harley Davidson motorcycle company uses a single fire ignition system on the models equipped with EFI, which now includes 100% of their product line with the introduction of the 2007 motorcycle models.
In 1991, Harley-Davidson motorcycle company began to participate in the Sound Quality Working Group, founded by Orfield Labs, Bruel and Kjaer, TEAC, Yamaha, Sennheiser, SMS and Cortex. This was the nation's first group to share research on psychological acoustics. Later that year, Harley-Davidson motorcycle company participated in a series of sound quality studies at Orfield Labs, based on recordings taken at the Talladega Superspeedway, with the objective to lower the motrcycle sound level for EU standards while analytically capturing the "Harley Sound." This research resulted in the motorcycle models that were introduced in compliance with EU standards for 1998.
On 1 February 1994, the company filed a sound trademark application for the distinctive sound of a Harley-Davidson motorcycle engine: "The mark consists of the exhaust sound of applicant's motorcycles, produced by V-twin, common crankpin motorcycle engines when the goods are in use". Nine of Harley-Davidson's motorcycle competitors filed comments opposing the application, arguing that cruiser-style motorcycles of various brands use a single-crankpin V-twin engine which produce a similar sound. These objections were followed by litigation. After six years, Harley-Davidson withdrew their motorcycle engine sound trademark application.
Electra Glide "Ultra Classic".
The Big V-Twins.
The F-head motorcycle engine, also known as JD, pocket valve and IOE (intake over exhaust), 1914-29 (1,000 ccm), and 1922-29 (1,200 ccm)
Flathead, 1930-1948 (1,200 ccm) and 1935-41 (1,300 ccm).
Knucklehead, 1936-47 61 cubic inches (1,000 ccm), and 1941-47 74 cubic inches (1,200 ccm)
Panhead, 1948-52 61 cubic inches (1,000 ccm), and 1948-65, 74 cubic inches (1,200 ccm)
Shovelhead, 1966-85, 74 cubic inches (1,200 ccm) and 82 cubic inches (1,345 ccm) since late 1978
Evolution (aka "Evo" and "Blockhead"), 1984-99, 80 cubic inches (1,340 ccm)
Twin Cam 88 (aka "Fathead") 1999-2006, 88 cubic inches (1,443 ccm)
Twin Cam 88B (counter balanced version of the Twin Cam 88) 2000-2006, 88 cubic inches (1,443 ccm)
Twin Cam 96, 2007-present, 96 cubic inches (1,584 ccm)
Evolution Sportster..
D Model, 1929-31, 750 cc
R Model, 1932-36, 750 cc
W Model, 1937-52, 750 cc, solo (2 wheel) frame only)
G (Servi-Car) Model, 1932-73, 750 cc
K Model, 1952-53, 750 cc
KH Model, 1954-56, 900 cc
Ironhead, 1957-1971 (900 cc), 1971-85 (1000 cc)
Evolution, 1986-present, 883, 1,100 and 1,200 cc
The Revolution motorcycle engine.
The Revolution motorcycle engine is based off of the VR-1000 Superbike motorcycle race program, developed by Harley-Davidson's Powertrain Engineering team and Porsche Engineering in Stuttgart, Germany. It is a liquid cooled, dual overhead cam, internally counterbalanced 60 degree V-twin engine with a displacement of 69 cubic inches (1,130 cc), producing 115 horsepower at 8250rpm at the crank, with a redline of 9000rpm. It was introduced for the new V-Rod line in 2001 for the 2002 model year, starting with the single VRSCA (V-twin V-Twin Racing Street Custom) model.
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