OEM replacement fuel petcocks

Even though it is a simple component that often receives little attention, Harley-Davidson has used several types of fuel taps over the many decades that the factory has existed.

Until 1939, petcock valves with tapered pipe threads were used. This applies to all IOE models, singles, 750s and other SV models, and early Knuckleheads. The 1/8” threaded valves had only an on-off position, while the 3/8” threaded valves also had a reserve position. The outlet of these valves is always threaded for a cap nut. Connectors for flexible lines did not become available until the 1960s.

Thru-tank-fuel control

In 1940, a new type of tap was introduced for all air-cooled V-twins, with the operating shaft mounted from top to bottom through the tank. No more fumbling under the tank, where you might burn your fingers, but the bottom of the tap and the guide had to be aligned very precisely for the tap to work correctly. A special tool and experience were needed for precise alignment.

Pipe threads and metric threads

That is why, from 1966, taps with a 3/8” pipe thread and reserve position came back. From 1975, the switch to metric connection threads with sealing washers came into production and assembly as a further simplification. There are basically two types of these with differences in operation: only with lever and with lever and a vacuum nipple.