Bendix Carb For V-Twin Harley
Originally fitted to sixties Harley-Davidson Big-Twins and Sportsters, the Bendix carb is a popular choice for classic motorcycle builders and restorers who still ride their old scoots. They are relatively simple units that easy to mount and easy to tune. The three styles made for Harley V-twins are a 38mm fixed main jet, 38mm adjustable main jet, and 40mm adjustable main jet.
Bendix Carb with Adjustable Main Jet
An updated version of the Bendix carb with adjustable main jets is currently sold under the name Zenith-Bendix. These are not necessarily better, but they do offer more tuning options. Properly set up, they will provide good performance and gas mileage.
Bendix HD Carburetors
Big-Twin Harleys came equipped from the factory with 38mm Bendix carbs from 1971 through 1975. In 1974, the FL Touring models switched to Keihin, while the FX models continued using the Bendix. From 1972 through early 1976, Sportsters were fitted with the 38mm Bendix. The larger, 80 cubic-inch BT motors may work better with the 40mm units.
Bendix Carb Rebuild
The Bendix HD 16P12 unit seen in this article is from my old 1976 XLH Sportster. It is the fixed main jet style. Like the other models, it has a dual venturi and uses an accelerator pump.
Shop Tools and Supplies at Zoro
Carburetor removal and disassembly is straightforward. It is held to the intake manifold with two bolts. The throttle-body is held on by the main jet tube assembly at the bottom of the carb. A 9/16" socket removes it.
After completely disassembling, check all parts. If the float is gas-soaked, replace it with a new one.
Clean the Carburetor
Consider investing in a gallon can of Berryman's Chem-Dip (about $25) and soak the body and float bowl (not the float). This stuff will dissolve the old dried-up remnants of fuel and remove any sludge. Be careful - Chem-Dip will eat plastics, puff up gaskets, remove paint, and other nasty things.
To get a good cleaning without soaking the carb in Chem-Dip, spray down into the fuel wells enough to make it puddle, then let it sit overnight. After soaking, rinse the carb parts with water and blow dry. A little brushing from a nylon brush will help clean up nice.
Around the top of the brass fuel tube assembly there is a fiber washer and an O-ring. The O-ring will rot away over time and will allow fuel to leak into the intake manifold. There should be a new one in the rebuild kit (buy a quality kit). Harley still sells the USA Zenith part under number 27762-71TA.
After blowing out all fuel circuits and air passages with compressed air, reassemble the carburetor. Allow parts to sit (preferably overnight) to ensure all parts are dry. Remember to install the new throttle shaft seal.
If you have an original Harley Bendix carb, you may want to re-use the old steel needle, as the newer ones are Viton-coated, which may have issues with some of today's gasoline alternatives.
Bendix Carb Float
Turn the carb body upside down and install the new bowl gasket. Float clearance is measured from the end of the float to the gasket, and should be 3/16". An easy way to measure this is with a 3/16" drill bit.
Once the carb is rebuilt and back on your bike, screw the main jet needle (closest to the air cleaner) inward until the spring is almost but not quite coil-bound (the original spring is about 5/8" long). Then turn the needle four full turns out. Next, set the low speed needle (closest to the engine) one full turn open from the closed position. After starting the engine, some minor adjustments may be needed to "dial it in".
Bendix Carb Rebuild Tips
- Use a quality gas filter before the carb inlet.
- Re-use or get the carb support from backing plate to lifter block.
- Swap the original PUSH throttle cable to the PULL throttle cable.
Being a compact unit, the Bendix sits "tucked in" and allows you to run almost any type of air filter. Round chrome is a popular choice. The one in the picture is an old Gary Bang unit.