That is not a 12v connector. It looks like an antenna connector - perhaps the looms are standard across the bikes and the roadmaster uses it.
The 12v connector is often taped onto another bunch of wires and you might not see it for the tape. Look for a bulky connector to see if it's taped on there. On the early bikes it was on the right side of the bike, but there was a change at some time and it was moved to the left. It won't be connected to anything unless a previous owner used it for something.
The wires will be black (ground) and gray/white stripe (switched power).
Many of the connectors are labelled. Look for one that has FR_12V_SWITCHED or similar.