Installed clamps on the intake manifold boots and that took care of the vacuum loss....a previous owner failed to install clamps when the carbs were removed, it appears. I drove the bike a few miles today and it seems to run quite well. The mufflers appear to have been swapped from another donor. The hangers are home made and the mounting clips appear to be in the wrong place.(?) Probably had some bad mufflers and someone changed then at some point.