The "EZ-Just"© idle mixture needle for Keihin carburetors

The following steps outline the procedure for installing the Keihin Constant Velocity (CV) and “EZ-Just ©” idle mixture needle screws.  We suggest having the appropriate service manual available for reference.

1. Following the proper service manual, remove the carburetor from your motorcycle.

2. Locate the soft aluminum plug that seals the idle mixture adjustment needle screw.  On the CV carburetor, it is on the bottom toward the spigot end of the carburetor.

Note: The plug may have been removed in order to tune or rebuild the carburetor. If so, proceed to step 5.

3. This step requires a 1/8” drill and short self-tapping sheet metal screw. Drill into the plug approximately 1/8-1/4”. Be very careful not to go to deep and damage the needle screw.

4. Screw the sheet metal screw into the hole in the plug.  Pull the plug and screw out together with a pair of pliers.

5. With a small flat bladed screwdriver, remove the idle mixture needle.

CAUTION! There is a spring, washer and o-ring under the needle! Do not loose these!If they are missing, a repacking kit is available.

6. Install the new needle into the carburetor make sure the spring and washer are installed correctly! From the adjustment knob end it is Spring, Washer, O-ring.

7. Turn the needle in until it gently seats.  Then, back out 1 ½ turns. This establishes a starting point for final adjustment.

8. Following the service manual, reinstall the carburetor.

9. After installing the carburetor, check for fuel leaks.

10. Start the engine and warm up to operating temperature.

11. Adjust the idle mixture for proper engine operation. Turning the needle in leans the mixture. Turning it out richens the mixture. See note below.

Note: EPA and most states require that the idle mixture be set to a standard. The adjustable needle is meant to allow you to adjust your idle mixture properly. Failure to do so will violate state and federal law.

Also see Mark's site HERE.