723735 Fits S S Super B D E and G Series Bendix Zenith and Keihin B

The Zipper’s Thunderjet kit introduces a patented third fuel circuit to traditional carburettor setups, specifically designed to rectify lean conditions at high RPMs and improve midrange performance. This mechanical upgrade features a built-in air correction system that stabilizes fuel delivery across varying altitudes and atmospheric conditions. It is a staple modification for Harley-Davidson riders using S&S Super B, D, E, and G series carburettors, as well as Bendix and Keihin units. By providing an additional source of fuel when the main jet reaches its limit, the Thunderjet ensures a consistent power curve and prevents engine overheating caused by lean mixtures. Note that S&S Super E and G models will require rejetting during installation.