The sub assemblies and components that make up this Cam Chain include this Adjuster Assy,tensioner, the most expensive part.
The O Ring(d:1.9,id:5.7) is the cheapest item from this partsfiche.
The eighteen Gsx550es 1987 (h) (e02 E04 E21 E22 E25) Cam Chain component parts are all listed in this schematic.