Keihin CV CVK CV40 Carburetor Harley



Harley Keihin CV EZ-Just mixture screw history


The Harley Keihin CV 40 carburetor is an excellent performing carburetor once it is set up correctly. Cyber Dave (founder of Direct Parts/CCP, and creator of the EZ-Just) found he was constantly getting his arm burned on the cross-over pipe when he was setting up CV carbs on the Dyno at Direct Parts. He tried using thick rags, welders cloth and even some exhaust matting but it he was always burning his forearms. Another pet peeve was the linearity of the adjustment. A seemingly small turn of the idle screw often changed the mixture considerably. Having the ability to adjust the mixture without burning your hands and without use of tools was the inspiration for the EZ-Just.

While the EZ-Just has since been copied and imitated by way of knock-offs and poor quality imports, there is only one original. Following the close of Direct Parts, CV Performance continued production of the EZ-Just and remains the only manufacturer of the original today. In addition the EZ-Just along with all other CVP products are proudly made in America.

Considerations when beginning to tune the CV carburetor. While the engines have changed the basics remain the same.

  1. No leaks in the intake tract. An intake leak makes adjusting the idle mixture properly impossible.
  2. The ignition system must be in good shape, new or nearly new plugs, good wires, coil and properly timed.
  3. An engine with poor sealing piston rings will be difficult or impossible to adjust properly.
  4. Jetting must at least be in the ball park to start with. Too often, a oversized pilot jet has been installed into the CV to overcome the "lean pop" making fine tuning difficult. If you are not sure of your jetting, here is a revised article on tuning the Keihin CV and other carburetors.