On this parts fiche the Gasket,rubber,10. is the most specified component.
A sample from the products for the Gasket Kit B include: O Ring 8.5x1.7, Wash.o-ring Kit,b, Washer Seal, 6mm, O-ring,5.5x1.4.
The twenty-one Xr650r 2000 (y) Canada / Ref Gasket Kit B component parts are all listed in this schematic.