Parts such as the Cam Chain: O Ring(d:2.4,id:20.8), O Ring(d:1.9,id:5.7), Screw,tensioner Adjust, Bolt 6x12 are included in the Gs450s 1985 (f) Finland Italy Austria (e15 E34 E39) Cam Chain parts fiche.
The sub assemblies and components that make up this Cam Chain include this Adjuster Assembly,tensioner, the most expensive part.
In this schematic the "Screw" is used most often.