I don't know anything about a KH100, but are you sure about the year? I didn't see a KH100 for that year listed at Partzilla.
The owner's manual should have the oil change info. Lacking the OM, there may be a decal or decals on the motorcycle somewhere with oil change & tuneup info. maybe on the back side of a side cover or under the seat somewhere.
1981 KZ650-CSR. Competition, Sports & Road.