If you have them at all they may be called a Fuzion or something. They were sold from 1986 until 2005 essentially unchanged. Hands down the best city commuter ever made. 77 mph top speed, comfortable, great MPG.
Riding it flat out on a crowded highway is not for the faint of heart however.
Anyway, the horn is not exposed. It's behind the plastic body panels yet it can still make people on the sidewalk jump if you beep it. It's not as loud as those air horn units but there's no need for a relay. Just plug in the factory connectors.