It is becoming difficult to find parts for a Solex carburettor. The most popular replacements that have abundant parts availability and are more versatile are the Zenith, Rochester and the Weber 1V carburettors. Replacing the Solex with any of these carburettors requires jetting to prevent engine damage due to a lean mixture. The Solex uses a #125 in general use and #110.5 for economical fuel consumption in the city. Sometimes the Solex just needs to be adjusted and does not need parts.
Start the engine and allow it to reach normal operating temperature.
Adjust the idle mixture screw. There are two screws on the driver's side of the Solex carburettor. The small screw closest to the manual choke cable bracket is the mixture screw and the screw closest to the firewall is the idle adjustment screw. Turn the mixture screw clockwise until the engine rpm begins to drop. Turning the screw counter-clockwise will raise the rpm. Turn this screw until the rpm is no longer rising. Once the maximum rpm is reached, turn the screw clockwise again just until the rpm begins to drop. Now turn the screw counter-clockwise ½ turn and leave it there.
Adjust the idle screw by turning it into raise the rpm and turning it out to decrease the rpm. Set the screw to idle the engine at 700.