In this schematic the "Nut, Hexagon (663)" is used most often.
Parts such as the Optional Parts Gauges & Component Parts 3: Thermo Unit, Damper, Bulb (t6.5, 12v-1.7w), Washer, Spring are included in the L250trp 1991 Optional Parts Gauges & Component Parts 3 parts fiche.
The Yamaha OPTIONAL PARTS GAUGES & COMPONENT PARTS 3 has twenty-three products enlisted in the schematic.