In this schematic the "Screw-washer,5x12" is used most often.
Some items from this specific schematic: Plate,air Cleaner, Band,air/c.tube, Plate,air Baffle, Bolt,wash 6x12.
The most reasonably priced component used on the Z50r 1983 (d) Usa Air Cleaner is the Bolt-washer,6x16.