Those of us who rode the 1500 are familiar with this type of rear brake problem. The design of the brake line connecting the front to the rear has a high point in it and after the bike sat for a while, such as over a bad winter I would have had no rear brake, because any air in the system would collect at that high point. It took a pretty tedious bleeding but eventually the air bubble would come out.
Now it seems that the 1800 has a similar problem. In searching this forum I came across "The Rocky Bleed" I don't know Rocky and I hope that he doesn't mind but I will post it in the next post. I have not done it yet but I will soon..
2012 Corvette GS Roadster Red
1999 Valkyrie Interstate Black
2006 GL 1800 White
2000 GL 1500 w Champion Escort Hack
Patriot Guard Asst. State Captain and Road Guard