I'm confused by comments here. The 750 has a rotating magnet and a stator coil. So does the GL1000 and so, I thought, does the CBR600RR. The RR I got has 3 yellow wires for the stator output, a red for 12v and a green for ground. To my knowledge, none of these bikes have a field coil so output is not adjustable.
Yes, Scottly, 13.4 does seem low. I figure 14.3 or so is about right.
Don R is correct. Lots of Naked Goldwingers have made this swap.