.125in Bypass Pill Main Jet

The .125in Bypass Pill Main Jet from ENDERLE is a precision fuel metering component designed for carbureted engine tuning and performance modification. This small but critical jet controls fuel flow through the bypass circuit of high-performance carburetors, making it essential for drag racing, street performance builds, and custom engine applications where fuel curve optimization is non-negotiable. Built by ENDERLE—an industry standard for racing fuel system components—this main jet addresses tuners who demand exact control over air-fuel mixture during acceleration and load transitions.

The .125-inch (0.125") orifice diameter of this bypass pill jet precisely regulates fuel metering through the bypass circuit, which enriches the mixture during acceleration and throttle blipping. The compact design—measuring 1.55 x 0.4 x 2.5 inches and weighing only 0.01 lbs—allows for seamless integration into ENDERLE carburetors and compatible racing fuel systems. Precision-machined from durable materials, this jet withstands high fuel pressure and ethanol-blended racing fuels while maintaining exact flow characteristics across engine RPM ranges. Bypass circuit tuning is critical for eliminating flat spots and lean hesitation during gear changes and hard acceleration.

This bypass pill main jet is ideal for bracket racers, Pro Stock builders, and street performance enthusiasts running ENDERLE carburetors on small-block and big-block V8 engines. Installation requires carburetor disassembly and precise seating in the bypass circuit bore—a task suited for experienced tuners or professional carburetor shops. Proper jet selection depends on engine displacement, fuel type, boost level (if applicable), and intended RPM band; having multiple jet sizes on hand allows fine-tuning across different track conditions and fuel batches. Verify carburetor model and bypass circuit specifications before ordering to ensure correct fitment.