The model number is in effect the motor number of a bike. The motor number is stamped on the left crankcase. The numerals of the motor number preceding the letters indicate the year. The letters indicate the size and type of the motor.
For example:
41EL2037 would be a 1941 model with a 61 OHV motor.
38U1863 would be a 1938 model with a 74 SV motor.
Below is a list of some of the motor designations:
Model Years Description
D 1929 1931 45 SV
DL 1929 1931 High Compression 45 SV
DLD 1929 1931 High Speed 45 SV
E 1936 1950 Medium Compression 61 OHV
EL 1936 1952 High Compression 61 OHV
F 1941 1950 Medium Compression 74 OHV
FL 1941 1965 High Compression 74 OHV
FLE 1955 1965 Special cam police 74 OHV
FLH 1955 1965 High Compression Sport 74 OHV
G 1937 1963 Servi-Car with tow bar
GA 1937 1963 Servi-Car without tow bar
GD 1937 1941 Large body Servi-Car without tow bar
GDT 1937 1941 Large body Servi-Car with tow bar
R 1932 1936 Low Compression 45 SV
RS 1932 1936 45 SV with Side Car
RL 1932 1936 High Compression 45 SV
RLD 1932 1934 High Speed 45 SV
RLDR 1935 1936 High Speed Race 45 SV
U 1937 1948 Medium Compression 74 SV
UA 1939 1940 Low Compression US Army 74 SV
UH 1937 1941 Medium Compression 80 SV
UL 1937 1948 High Compression 74 SV
ULH 1937 1941 High Compression 80 SV
V 1930 1936 Standard Compression 74 SV
VHS 1934 1936 Medium Compression 80 SV
VL 1930 1936 High Compression 74 SV
VLD 1930 1936 High Compression 74 SV
VLH 1934 1936 High Compression 80 SV
W 1937 1952 Low Compression 45 SV
WL 1937 1952 High Compression 45 SV
WLA 1940 1945
1949 1952 US Army Low Compression 45 SV
WLC 1942 1943 Canadian Army Low Compression 45 SV
WLD 1937 1942 High Speed 45 SV
Note that the inch indications above are cubic inches.
