If an internet search didn't yield any result, then there may not be one. There might be a hard copy listed on eebbaayy.
Partzilla has parts diagrams & cross-reference. For a model that old I would save screen shots of all of the diagrams & save the x-ref info as well. Click a part for its cross-ref.
Partzilla >> OEM >> Kawasaki >> Motorcycle >> Year >> Model.
1981 KZ650-CSR. Competition, Sports & Road.