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 topend 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™! The ThunderJet™ is an additional high speed fuel circuit, delivering needed fuel to the engine at higher rpms, 4500 & up. You can now use the main jet to tune for smooth, broad mid-range power and supplement the top-end with the ThunderJet™. Jets are used to control the amount of fuel sent to the engine. Join thousands of satisfied customers worldwide!. ThunderJet™ kits come with complete installation and tuning instructions and extra jets. Fits all models of S&S carburetors. Machining to the carb bowl and body is required; we can install this on your carb for a reasonable cost.

This is the most cost effective horsepower per dollar you can buy!


Not legal for sale or use in California on any pollution controlled motor vehicle.
Not legal for sale or use on any EPA pollution controlled motor vehicle.

Weight 1 lbs

Emissions Compliant

Country of Origin

Fuel / Air

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