Parts such as the Oil Tank: Joint,oil Strn, Joint,oil Tube, Sw.assy.,oil Leve, Screen,oil Strn. are included in the Nsr125f 1989 (k) Italy / Kph Oil Tank parts fiche.
In this schematic the "Clip B10,tube" is used most often.
The lowest price component in this Oil Tank parts-list fiche is the Nut,flange,6mm.