The component with the lowest price in the CARBURETOR schematic is the Clip B7,tube.
Parts such as the Carburetor: Carburetor Assy (, Jet,main(#125), Carburetor,assy, Clip B7,tube are included in the H100s 1986 (g) England Carburetor parts fiche.
With two applications this Screw-washer,4x16 is the most specified part.