Pocket-sized calculator used to determine required jetting changes in Mikuni carburetors due to ambient temperature, altitude or both. Provides a guide for determining rich or lean carburetor conditions. Useful for single or multiple carburetors, 2-Stroke or 4-Stroke engines. A must tool for any serious rider. Learn what changes in jetting are needed on your Mikuni carbs due to ambient temperature, altitude or both. Use this Mikuni pocket tuner for all single- and multi-carb applications on two- and four-stroke engines. Primarily for adjusting the main jet.