[Mark in MT]

Stalling at a sudden stop is irritating, but fixable. If the throttle plate is not adjusted properly, the carb will not pull the fuel from the idle discharge port in the side of the bore. You will have trouble adjusting the idle mixture and raise the idle speed to compensate. Try loosening the throttle plate screws, and with the idle stop screw backed all the way out, tap on the plate while holding tension on the lever to close it. This will center the plate in the bore and place it near enough to the port to work right. Tighten the screws and hold it up to the light, it should almost black out the light. If there are warts, burrs, or pimples on the plate, remove it and dress it up with a file to get it smooth. Some of the plates have a notch or bevel on one side, that goes towards the port.

The idle jet must be sized correctly for your engine, if it is not right you can't get it to idle slow enough, and it will not run on the idle circuit. The idle circuit only operates at very slow idle. If you can't adjust idle quality with the air screw,it is idling too fast or the jet is the wrong size, or the idle port is plugged.

Properly adjusted, the Zenith will idle smoothly at 400 rpm and stay running during a hard stop. Once you get it right, it will run great.