Hi Steve,
What you likely need is a Patchmap for the Motif 8, dropped into the main bb folder, and selected as the default Patchmap inside BB.
The Patchmap would allow you to see and select the various banks of voices in the Motif, by name.
The pgmusic Patchmap sharing page is here:
http://www.pgmusic.com/support_miscellaneous.htm There are several different Motif models listed under Yamaha there, I don't know if any one of those matches the banks in your particular Motif or not.
And, if there is not a matching patchmap published above, not to worry, if you can locate a Cakewalk Instrument Definition file for your model, Band in a Box features a converter inside it that will automatically convert the Cakewalk .ins definition file to a Band in a Box Patchmap. A websearch can bring up Cakewalk instrument def. files that you can download for free.
See the BiaB FAQs for more information concerning Patchmaps and usage, including how to make your own file from scratch if need be. I doubt you need to go to that extreme, though, because of the sheer proliferation of Motif and the large Cakewalk user base.
--Mac