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Carburetor Tuning Quick Reference

Below: Functional Range Effectiveness of Tuning Parts in Relation to the Throttle Valve Opening Carburetor Tuning & Jetting

Shown in the Below Diagram are the operational ranges that the different jetting systems (Main Jet, Jet Needle, Needle Jet, Throttle Valve, and Pilot System) work in relation to the throttle slide position as it moves up and down inside the carburetor's throttle bore. As you see on the diagram there is also some cross-over effect between jetting systems, so a jetting change to one system, may also affect the operation of the jetting system next to it.

This basic Throttle Valve Opening Operating Ranges shown above also applies to Keihin Carburetors, but jetting components and sizing are not interchangeable between the two different brands. This section applies only to Street and Off-Road Carburetors, not Personal Watercraft Carburetors. If you are not experienced in Carburetor Tuning, we do suggest that you purchase and read our Mikuni Tuning Manual to give you a much better understanding of how the motorcycle carburetor operates, and how it and the engine are diagnosed, the carburetor disassembled, adjusted and tuned for the correct jetting and running.