Carburetors are identified by their size, to the "venturi" is to say the passage of the valve. The smallest passage. Beware many title are false by writting about the exit diameter.

The fixing is quite simple — two screw with a width of 48 mm (any carb from 18 to 30) or a clamp of a flange rubber diameter 33 mm (24 to 28 mm Mikuni and Keihin any carburetor)