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Harley-Davidson engines are a line of engines manufactured since 1903 in Milwaukee, Wisconsin by the Harley-Davidson company for use in its motorcycles. Harley-Davidson engines are now made at Harley-Davidson Motor Company's Pilgrim Road Powertrain Operations facility in Menomonee Falls, Wisconsin.

The company's founders started making smaller flathead motorcycle engines individually by hand and fitted to bicycles in the 10 ft x 15 ft wooden barn in Milwaukee that was the Harley-Davidson workshop of the time, prior to that in 1901.

That first engine was a single cylinder model, based roughly on the recently developed De Dion-Bouton internal combustion engine.

The company was soon fully committed to producing its own proprietary engine designs, and by 1909 the first Harley-Davidson V-Twin engine had been designed and made, setting a template for engine design that continues today.

Engine timeline

Light engines
Harley-Davidson engines
Engine		1900s			1910s			1920s		1930s				1940s	1950s	1960s				1970s				1980s				1990s		2000s	2010s
S																			1948–1952
One-cylinder engines
27.4" F-head	1903–1905
26.8" F-head			1906–1908
30" F-head				1909–1912
35" F-head						1913–1918
37" F-head									1921–1923
21" OHV										1926–1929
21" flathead										1926–1934
30.5" flathead												1929–1934
"Hummers"																					1948–1966
Topper																											1960–1965
Baja 100																													1969–1972
Big twin engines
F-head (IOE)							1914–1929
Flathead											1930–1948 (until 1973 in the servicar models)
Knucklehead															1936–1947
Panhead																						1948–1965
Shovelhead																													1966–1984
Evolution																													1984–1999
Twin Cam																													1999–2017
Milwaukee-Eight																													2017-
Sport engines
W (opposed)								1919–1923
XA																		1942
D											1929–1931
R													1932–1936
W (V twin)																	1937–1952
G (W engine)																	1937–1973
WR																	1941–1952
K																							1952–1953
KH																									1954–1956
KR																							1952–1969
Ironhead																										1957–1985
XR																													1970–
Evolution																													1986–
Fluid (water)-cooled engines
Revolution																													2002–2017
Revolution X																													2013–

Big Twin (Stock) Engine Sizes:

Flathead 45ci (737cc)
Knucklehead 60ci (983cc) & 74ci (1212cc)
Panhead 60ci (983cc) & 74ci (1212cc)
Shovelhead 74ci (1212cc) & 82ci (1343cc)
Evolution 82ci (1343cc)
Twincam 88ci (1442cc) & 95ci (1556cc) (88/96ci bore 3.75in (95.25mm) & 4.00in stroke on 88ci (101.6 mm)
Twincam 96ci (1584cc) & 103ci (1690cc)(96/103ci bore 3.875in (98.40mm) & 4.38in stroke on 96ci (111.25 mm)
2017-Milwaukee-Eight 107ci (1746cc) & 114ci (1868cc) & 117ci (1923cc)
2016-Milwaukee-Eight 114ci (1868cc)

References

Hornsby, Andy. "A Potted History of Harley-Davidson: Part 1 1903-1954". Crewe, UK: American-V. Archived from the original on 2011-02-11. Retrieved 2011-04-04.
Mitchell, D., ed. (1997). Harley-Davidson Chronicle - An American Original. Publications International Limited. ISBN 0-7853-2514-X.
Henshaw, Peter, Kerr, Ian, "The Encyclopedia of the Harley-Davidson", 2001, Chartwell Books, Inc., ISBN 0-7858-1274-1
Flatheads, Knuckleheads, Panheads, Shovelheads | A Guide to Harley-Davidson Engines, Devitt Insurance, 2021.

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