since the horn and starter button ground thru the handlebars (rubber mounted) most of these had a black grounding wire from the left switch into the headlight shell, the front fork itself is a poor ground as it's only contact points are thru the fork stem bearings or the clutch and throttle cables, this is why a ground wire back from anything on the front fork (turn signals, horn, starter button and headlight) to a good solid frame ground is important, then we get to the previously mentioned rubber mounted rear fender again a good ground is needed, I like to run grounds to the same point that the battery frame ground uses as stated "You can't have too many grounds"