Below is a comprehensive list of motorcycle engines produced by Harley Davidson throughout the years beginning in 1903 when William S. Harley and Arthur Davidson first started building in their insalubrious shed.
Single Cylinder Engines
27.4 Cubic Inch/449cc F Head single cyl 1903-05
26.8 Cubic Inch/439cc F head single cyl 1906 – 08
30 Cubic Inch/491cc F Head single cyl 1909-12
35 Cubic Inch/573cc F head single cyl 1913-18
37 Cubic Inch/606cc F head single cyl 1921-23
21 Cubic Inch/344cc OHV 1926-29
21 Cubic Inch/344cc Flathead 1926 – 34
30.5 Cubic Inch/499cc Flathead 1929-34
Topper 1960-65 The Topper had a 165 cc (10.1 cu in) single-cylinder two-stroke engine mounted horizontally. 
Hummers 1948 – 1966 – See Hummers Page
Aermacchi 1960 – 1978 – See Aermacchi Harley Davidson Page
Twin Cylinder
F Head 1914-1929
Flathead 1930-48 – until 73 in Servicar 45in 737cc
Knucklehead 1936-47 60in- 983cc or 74in 1212cc
Panhead 1948-65 60in-983cc or 74in 1212cc
Shovelhead 1966-84 74in 1212cc or 82in 1343cc
Evolution 1984-99 82in 1343cc
Twin Cam 1999-2016 88in 1442cc, 95in 1556cc, 96in 1573cc, 103in 1687cc
Milwaukee Eight 2017 onwards 107in 1746cc, 114in 1868cc, 117in 1923cc
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 onwards
Water Cooled engines
Revolution 2002 onwards found in the VROD
Revolution X 2013 onwards found in the Street
