A title is needed for a complete bike for export, generally these are issued by the dealer when bike is new (30 yrs ago) and passed from owner to owner, thats why it's rare to have an old mxer titled.
The bill of sale is a receipt from the current owner
An old bike can be titled for export, but not in all states of the u.s.
Generally the seller will strip the bike down into bits and send as parts, as a title is not required to export "parts"