Two versions of this airboot cover virtually all post-'72 Pursangs. The smaller one (part #144.15-166) fits carburetors with 2-1/4" airbells, like Bings, Amal Concentrics and Mikuni VM30-34s. The larger one (#143.15-166) fits 2-7/16" airbells, common to 36-40mm Amal MkII and Mikuni VM36-38 carburetors.