| Model | Year | Description | |
| W | 1937 - 1952 | low compression 45 Solo | |
| WL | 1937 - 1952 | high compression 45 ci with 3-speed transmission | |
| WLD | 1973 - 1942 | 45 ci extra high compression with 3-speed transmission | |
| WLDD | |||
| WLDR | Competition Special, 45 ci with 3-speed transmission and aluminum heads | ||
| WLA | 1940 - 1945 and 1949 - 1952 | US Army low compression 45 Solo | |
| XA | US Army | ||
| WLC | 1942 - 1943 | Canadian Army low compression 45 Solo | |
| WLH | 1950 | Special batch for Dutch Military Police | |
| WLJ | 1951 | Special batch | |
| WR | Race model | ||
| WS | Sidecar Twin, 45 ci low compression with 3-speed transmission and sidecar gearing | ||
| G | 1937 - 1973 | Servi-Car with tow bar, 45 ci with 3-speed and reverse transmission | |
| GA | 1937 - 1973 | Servi-Car without tow bar, 45 ci with 3-speed and reverse transmission | |
| GD | 1937 - 1941 | large body Servi-Car without tow bar, 45 ci with 3-speed and reverse transmission | |
| GDT | 1937 - 1941 | large body Servi-Car with tow bar, 45 ci with 3-speed and reverse transmission | |
| GE | 1964 - 1965 | Large Compartment Servi-Car with airtank, 45 ci with 3-speed and reverse transmission | |
| U | 1937 - 1948 | 74 ci medium compression with 4-speed transmission | |
| UA | 1939 - 1940 | Low compression US army 74 SV | |
| US | Sidecar Twin, 74 ci medium compression with 4-speed transmission and sidecar gearing | ||
| UL | 1937 - 1948 | 74 ci high compression with 4-speed transmission | |
| UH | 1937 - 1941 | 80 ci medium compression with 4-speed transmission | |
| ULH | 1937 - 1941 | 80 ci high compression with 4-speed transmission | |
| UHS | 80 ci medium compression with 4-speed transmission and sidecar gearing |
| Flathead, 1940 - 1952 Civilian models | |||
|---|---|---|---|
| W (Iron heads) | |||
| WL (Aluminum heads) compression | 6 to 1 | ||
| G (Servi-car) compression | 4.75 to 1 | ||
| Number of cylinders | 2 | ||
| Cylinder bore | 2 3/4 inches | ||
| Stroke | 96.85 mm / 3 13/16 inches | ||
| Wheelbase | 57 ½ inches | ||
| Average delivered power and RPM | 25 HP at 4500 RPM |
| Gear Ratios | ||||||||||
| Motor Sprocket | Clutch Sprocket | Countershaft Sprocket | Rear Wheel Sprocket | High Gear Ratio | ||||||
| Solo (iron heads) | 31 | 59 | 17 | 41 | 4.59 to 1 | |||||
| Solo (alu. heads) | 30 | 59 | 17 | 41 | 4.74 to 1 | |||||
| Sidecar | 27 | 59 | 17 | 41 | 5.27 to 1 |
| Tire Inflation Pressures | ||||||
| Solo | 4"00 tire | Front | 12 lbs. | Rear | 14 lbs. | |
| 5"00 tire | Front | 12 lbs. | Rear | 12 lbs. | ||
| Servi-Car | 4"00 tire | Front | 12 lbs. | Rear | 20 lbs. | |
| 5"00 tire | Front | 12 lbs. | Rear | 16 lbs. |
Flathead pictures in the Gallery
Information per year
Sources: Bruce Palmer: How to restore your Harley-Davidson
Greg Field: Original Harley-Davidson Panhead
Peter Henshaw: The legend of Harley-Davidson
Harley-Davidson Panhead Service Manual - 1948 - 1957
This board and various other sources