There is a wire bundle wrapped in black electrical tape that emerges from under the headlight housing on the right side and then snakes back between (and under) the gas tank and frame member.
The turning of the handlebars rubs this bundle against the right side fork stop. The fork stop is a welded on metal flange.
On my bike I noticed this was rubbing through the black electrical tape - just to the point of bare wire insulation showing. I repositioned this wire bundle upward where it doesn't rub anymore. I recheck it everytime I think about it - as it has a tendency to want to work it's way downward with handlebar motion.
I don't know if this is your problem but it should be looked at and checked.
Regards, Foggy