Here is, how I mounted my Garmin Zumo 660 to the handlebar of my CB1100.
GPS in action looks like this:
The handlebar mount I bought by a German motorcycle parts distributor (click pic for more info):
[url=https://www.louis.de/en/artikel/verstellbarer-navi-halter/10001504?searchButton=&filter_article_number=10001504]
For my purpose I removed the middle part of the 3-part-mount, to get the socket close to the handlebar. At this picture the Garmin itself is unmounted from the covered socket:
The Zumo 660 comes with a socket and a cable for installation. From behind you can see, how I screwed the socket directly to the plate of the mount:
I'm quiet satisfied with this solution. The GPS is centered within the other controls and I don't have to look much around to find all information on a short glance, not too much distracted from traffic around.
Only thing, which could be better: the plate is a little bit to wide, it could close edge-to-edge with the socket.