Building a Bronson Bike - The Carburetor

In 1957 the first Harley Davidson Sportster rolled out of the factory in Milwaukee Wisconsin, These first-year bikes breathed through Linkert DC Side float carburetors. Linkert carburetors were also used on the Sportster's forerunner, the K Model, beginning in 1952.

K Models were flat heads and Sportsters have overhead valves. But from below the bottom of the cylinders, including the primary drive set-up and transmission Sportsters and K Models are the same.

Zenith Instruction papers

In 1966 Harley introduced Tillotson carburetors on Sportsters. Tillotsons were used for 6 years, until 1971. History has not been kind to the reputation of these carburetors, mostly because they don't operate exactly like a float bowl equipped carburetor. Tillotsons have a rubber diaphragm that is controlled by engine vacuum and pumps gasoline directly from the gas tank into the fuel stream. What really drove people crazy was the fact that differing weather conditions required slight adjustments to the idle mixture thumb wheel located directly on top, within easy reach. The service manual says to limit your adjustments to 1/8th of a turn either way, NOT more!

You will then need a throttle cable retaining bracket to hold the cable stationary as the hard-wire moves back-and-forth as you work the throttle. Note the bracket and the part number, of course this is obsolete, but can be found with research or homemade. Throttle cable retaining bracket No.25

In 1972 Harley went back to a conventional style carburetor. Bendix Zenith carburetors were used until the first half of 1976 and were a definite improvement. No more fiddling required based on the weather and no more vapor lock tendencies in hot weather. In 1911 Zenith Carburetor Company began production in Detroit, Michigan.

Years later, Bendix Corporation purchased Zenith and continued production using the Zenith name. Interestingly, in the early years, there was also a Zenith carburetor company in England, which was not in any way connected to Zenith in America.

From late 1976 to 1987 Harley sourced carburetors from Keihin in Japan. They were basically Zenith style carburetors with even more accurate fuel metering and with the precision Japan is famous for.

From 1988 to 2006 Keihin CV (constant velocity) carburetors were fitted to our beloved Sportsters. CV carburetors meter fuel based on engine speed, regardless of throttle position. This minimizes over-rich conditions resulting in a cleaner running engine with less pollution.

From 2007 on, all Sportsters are equipped with fuel injection. No more hand chokes, float bowls, screwdriver adjustability, or fuel shut-off valves. That makes a lot of people happy, but Not me!

Carburetor history courtesy of Peter