Here is one of the ways to do this. In performance mode, select Job mode and initialize the current performance. (Nothing is wiped out until you decide to write it to memory). In edit mode, assign the sounds you want to 4 of the parts. For this procedure, keep layer off on each part. Light the master keyboard button. The A B C D buttons represent each zone. Assumming the sounds are all from the S80, TG should be on for each zone. TrnsCh should match RcvCh for each part. By default, the receive channels are the same number as the part. By default, the zone transmit channels are all set to 1. The best thing to do is to leave the receive channels the way they are and match the transmit zone. On the 2nd page of MKB you will find the note limit parameters. Set the low and high note limit for each zone. This should get you started.
Have you visited
www.yamahas80.com yet? There is an email based forum you can sign up for.
Bill Mocarsky