A .016 wires spring is the most commonly used, however, .020 and .024 are also available. Using a thicker wire spring will give more spring tension, resulting in a richer fuel mixture at idle and low rpm operation.

The jet (pill) controls the amount of fuel the engine will receive at all rpm ranges. The larger the jet size, the more fuel is allowed to return to the tank, therefore leaning out the mixture. To richen the mixture, use a smaller jet size. To lean the mixtrue, use a larger jet size.

Drop the jet into the valve so the number is visible to you. This side of the hole has been champfered and is the side that fuel enters.

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Details

This brass valve is designed to control high rpm, closed throttle fuel pressure. It consists of a body, cap, poppet, spring, a .187” shim, and seal. The body is marked with the letter “S” and an arrow. It connects directly off the metering valve, with the arrow pointing toward the fuel tank. Since fuel flow is controlled mechanically by the metering valve, any open throttle position 25 degrees or more will automatically shut of the Secondary By-Pass Valve. This eliminates the possibility of a lean condition when throttle is open. Shims and springs can be added to change fuel pressure.

AN Thread Sizing Guide

Ratings & Reviews

3 Reviews

Overall Assessment

Customers appreciate the bypass valve for its top-notch quality and perfect fit. It stands out as a precise replacement for faulty ones and has been proven to efficiently improve engine performance, particularly providing smoother restarts after caution periods, which points to its practicality and usability. These attributes set it apart and compel users to highly recommend it, especially to those in the racing sector. Its affordability is also emphasized, making it a superior choice compared to competitor products.

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3 reviews

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The bypass valve worked perfectly. Very good product.

5.0

9 years ago

Bill

New Hampshire

Verified

It is an exact replacement for the one I have that went bad.

Would Recommend

Great product

5.0

10 years ago

Mike

Emmaus Pa

Verified

Great price and awsum service and shipping in time for racing thanks speedway motors!

Would Recommend

The engine had Stumblitus !

5.0

10 years ago

Sid

Salem In.

Verified

We use these valves to help get a better restart after a caution period . The engine takes off smoother .

Would Recommend

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