Carburetor Float Level Gauge

Description

Carburetor Float Level Gauge | Honda CT90 through CB750

A purpose-built float level gauge for setting carburetor float height on vintage Honda motorcycles. Stamped from steel with laser-etched millimeter markings, this gauge gives you a fast, repeatable measurement every time you rebuild or adjust your carburetors. It works on all Honda models from the CT90 Trail 90 through the CB750any Keihin carburetor with a measurable float.

Why You Need This

Every carburetor rebuild requires setting the float height. The float controls how much fuel sits in the bowlset it too high and the engine floods, set it too low and it starves for fuel at higher RPMs. Honda specifies a different float height for nearly every model, and getting it wrong causes noticeable running problems.

This gauge is adjustable for a wide range of carburetor styles. It is marked in centimeters (1, 2, 3) with each millimeter noted in between. To read a spec like “21 mm,” look for the mark just past the “2” line.

How to Use

1. Remove the float bowl from the carburetor body.
2. Hold the carburetor with its main bore vertical so the float arm tang just closes the float valve without compressing the spring-loaded pin inside the needle valve.
3. Position the gauge on the gasket sealing surface and read the measurement at the highest point of the float.
4. Compare your reading to the factory specification for your model (see chart below).
5. To adjust: Remove the float pin and gently bend the small metal tab on the float hanger that contacts the float needle. Bending the tab inward lowers the mm reading (raises the fuel level); bending outward raises the mm reading (lowers the fuel level).

For carburetors with two floats, measure both sidesthey should read the same. If one side is off, the float hanger may be bent or twisted.

Specifications

Honda Factory Float Height Specifications

These are the factory-specified float heights for each model. Always measure from the gasket sealing surface to the top of the float, with the float tab just touching the needle valve without compressing its internal spring.