Zippers Thunderjet Tuning Kit Harley Keihin CV & S&S Super E B G D Carb

The ThunderJet™ is a jet-able, externally mounted third fuel circuit designed to dramatically improve the performance and tuning capabilities of your carburetor. By adding a dedicated high-speed fuel circuit, the ThunderJet™ allows existing fuel circuits to be more precisely tuned to specific power ranges, resulting in a significantly more balanced fuel curve and improved throttle response.

Standard two-circuit carburetors typically rely on an intermediate circuit and a main jet circuit to cover the entire RPM range. This often forces riders into a performance compromise: tuning for crisp mid-range response can leave the top-end lacking, while increasing the main jet for top-end power often causes the mid-range to run rich, leading to flat spots or hesitation. The ThunderJet™ solves this problem by delivering necessary fuel to the engine at higher RPMs (4500 and up). This allows you to utilize the main jet to tune for smooth, broad mid-range power while supplementing the top-end independently.

Performance Benefits:

• Eliminates flat spots and hesitation throughout the RPM range.
• Provides a significant increase in power felt across the entire (extended) RPM range.
• Allows for a more balanced fuel curve and finer tuning of specific power ranges.
• One of the most cost-effective "horsepower per dollar" upgrades available.

Technical Specifications & Compatibility:

The ThunderJet™ is compatible with Keihin CV carburetors as well as all models of S&S carburetors. Please note that installation requires minor machining to the carburetor body and float bowl to accommodate the new circuit. For owners of Keihin CV carburetors, a flat-backed air cleaner assembly (such as Zipper’s or the Screamin’ Eagle®) is required for proper fitment.

Each kit comes complete with comprehensive installation and tuning instructions, along with extra jets to ensure you can achieve the perfect fuel delivery for your specific engine configuration. Join thousands of satisfied riders worldwide who have optimized their Harley-Davidson® performance with this essential tuning tool.

Harley Keihin CV Carb Carburetor