In this schematic the "Collet" is used most often.
Parts such as the Valve(s): Shim,t=3.45, Shim,t=2.90, Shim,t=2.95, Valve-intake are included in the Zx400l4 Zxr400 1994 United Kingdom Fr Nl Ar Fg It Valve(s) parts fiche.
Of all the components that make up this Valve(s) the O Ring,15mm has the lowest price.