If your motorcycle is running lean, one idea to consider is to rejet your motorcycle carburetor. Putting in larger jets will give you greater performance and a smoother ride in situations that require a richer mixture of fuel. Especially with Harley Davidson motorcycles, carburetor rejetting can be accomplished easily by the backyard mechanic.
1. Fine tune your motorcycle before rejetting your carburetor. If it’s still running too lean, you can replace the pilot jet as a first step
2. Remove the bowl at the base of the carburetor by unscrewing the screws holding it in place. Unscrew the pilot jet inside, but be careful not to strip it. The jet size will be on top.
3. Use a screwdriver to remove the main jet from the brass jet needle holder, which is also called the emulsion tube.
4. Put in a pilot jet that is one size larger. Replacing it with a jet two sizes larger will make your mixture too rich.
5. Tune the slow/idle settings before replacing the main jet. Replace the main jet with one size larger. The sizes are in increments of 5.
6. Put the bowl back on, and align the accelerator pump shaft and rubber boot.
7. Reinstall the carburetor on the motorcycle and retune it to finish the rejet procedure.