Harley Evolution CV Carburetor Upgrade

Our 1988 Heritage Softail is going to have a noticeable increase in performance when Mike replaces the original Bendix carburetor with a CV carburetor. The Bendix carburetor was a good carburetor in its day. However, the Bendix carb could be problematic and inconsistent. Harley Davidson used the CV carburetor on all carbureted models from 1990 until 2006. The CV carburetor is versatile, dependable and very consistent.

Mike removes the stock air box. This consists of the air cleaner cover, baffle, air filter element, and backing plate. The backing plate is secured to the carburetor with three 1/4″ button head screws and is secured to the front & rear heads with two 5/16″ allen head bolts.

This early Evo has a bottom breathing motor. The motorcycle still has the original breather hose that runs from a fitting at the bottom of the crankcase up to the left side of the air box. This breather hose will later be rerouted to the ground.

Mike is also updating the intake manifold. The stock intake consists of front and rear compliance fittings. The compliance fittings tend to dry out and crack causing air leaks. Compliance fitting leaks are also caused by constant expansion and contraction. A solid Harley Davidson intake manifold will be used upon reassembly. The solid intake will be mounted to the front and rear heads with flanges and 5/16″ allen head screws. When removing & installing compliance fittings or intake flanges, it works well to use a long 1/4″ ball allen on the right side and a 1/4″ offset allen on the left side. A short 1/4″ allen bit with the box end of a combination wrench can also be used on the left side.

Mike removes the original choke cable and the throttle cables. These can not be used with the updated carburetor. The internal cable for Bendix throttle cables is too short for use with a CV carburetor. Choke cable configuration is completely different between the two carbs. In fact, the CV carburetor does not even have an actual choke. The CV has an enrichener cable. Pulling out on the cable does not restrict air like on the Bendix. It opens up a fuel circuit within the carburetor.

Watch our Multi-Hour Carb Project