right horn ground location?

[schrocketeer]

Would you please help me with where the ground (or earth, negative return) for the right horn is located? '85 K100RT.
A previous owner had daisy-chained the ground from the right horn, to be the ground for an aftermarket driving light. I pulled the lights, now I'm sure where the horn originally grounded.

[rbm]

Any convenient ground point will work. The horn wires from the harness are paired normally - one powered (green/grey) and one ground (brown).  If those still exist, just use it.  If not, run a new ground wire.