I too had a problem with the back brake even after vacuum bleed - hung caliper - standard bleed then settled for a soft peddle. The next day I rode and parked the bike. The following day I bleedd it again and a small amount of air came out. Brake OK now.
Question-
On the dual disc speedmaster do you let both calipers hang while bleeding?
On an auto you do the brake furthest away from the master cylinder first. Is this what you do on a motorcycle?
Thank for you help,
Gary