ThunderJets™ for S&S® E/B Carburetors

ThunderJet™ is a jet-able, externally mounted third fuel circuit that improves the performance of 2-circuit carbs such as the S&S Super. Unmodified, these carbs typically have a low speed, or intermediate, circuit that supplies fuel from idle to approximately 2500 rpm, at which point the carbs’ main jet circuit becomes active, delivering more fuel to the engine. These two circuits must then supply fuel for the rest of the rpm range. The problem is: the remaining rpm range is too wide (typically 2500-6500 rpm) for only 2 circuits to handle efficiently. The tuner generally encounters problems jetting the carb to give good, crisp mid-range response and still have strong top end power. A compromise is the result. Back the main jet down, carburetion in the mid-range is good but top-end is lacking. Increase the main, top-end improves but now the mid-range is rich; flat spots or hesitation is encountered. The answer? ThunderJet™!