IIRC, this is NOT possible, simply because the handlebars are positioned directly over the tops of the fork tubes. You MIGHT be able to install bar-risers or bar-bacs to move the handlebars out of the way of the fork tubes, but that might not be suitable for your purposes.
If you own or have access to that CB125, post a top-down photo of your handlebars and fork tubes, so we can see the alignment. and try to help you figure out a work-around to solve this.
