Modern Vespa

Is there a Stebel (loud) horn that I can install on my GTS 300 without modifications. I mean, really, just using pliers and a screwdriver? The stock horn is just too anemic for a college town.

Thanks, everybody. I have really learned a lot of valuable things from this forum. I am always impressed with the high level of expertise you all show, as well as your willingness to help the Vespa-challenged.

Here's a place to start: Another new smaller, LOUD, Stebel for scooters...

Thanks for the tip. I read the entire thread and it looks like the Stebel TM80 would bolt right in, but may have problems over time with burning out the horn switch? I would put a relay in if I could figure out how. I sort of know what a relay is, but how does it work in terms of preserving the switch?

A relay is really just a switch in itself. You are switching a low current relay when you press the horn button. The relay then closes and allows higher current to flow through the relay (not through the button) to the horn. That way you are not using the horn button to switch the higher current.

However, I've had the Stebel Magnum on my LX150 for several months with no problem. IMHO unless you are regularly laying on the switch for extended periods you should never generate enough heat to damage the switch with this horn. Now the Nautilus is a different story. There you would definitely need a relay, not only to protect the switch, but also the wiring.

Circuit 1 below shows some lights being switched without a relay.
Circuit 2 shows the relay in place.
Note that without the relay the switch is taking the full 20 amps, but using the relay the switch is only having to handle 1/4 amp.

1) Never admit to hornlessness. Its a personal detail we don't need.

2) The Stebel Magnum is for you. Not as aloud as the Nautilus, but REAL LOUD. And probably won't fry your horn switch.

Here, check this thread, has a great diagram for relay hookup.
Tutorial: Installing a Stebel Airhorn on a GTV

Jack