The thirty Cn250 Helix 1991 (m) England Mph Right Crankcase Cover component parts are all listed in this schematic.
A sample from the products for the Right Crankcase Cover include: Drain Cock, Washer,plug,drain 12, O Ring, 30.8m/m, Bolt,flange,6x80.
On this parts fiche the Bolt,flange,sh,6x40 is the most specified component.