Modern Vespa

This one is new to me. I am still scratching my head trying to understand it. So I have a 78 P200E with double yellow stator and a battery. From the 11 years that I owned the P200E the rear tail light, turn signals, horn, neutral light has ALWAYS operated with the battery.

My head light bulb has blown out at least 3 times in the past years (sealed factory beam) but when I put the Stella style headlight with halogen bulb it gets super bright when you rev it but it has never blown out. I read 17+ VAC at the headlight connector and I understand that this is unregulated voltage but that is not the issue today .

The problem that I am having right now is that all the sudden all my turn signals, neutral light, tail light , horn and back tail light are lit up with the battery disconnected however everything is very dimmed.

I noticed for a few days that my headlight was very dimmed with the battery disconnected. I let down my guard, I was confused in a way that I saw my rear tail light operating and I assumed that the battery was connected... but you see, I just never ride in traffic without the battery disconnected because I need a good working tail light, brake light, horn and turn signals.

My first thought today was that I swapped out a spare double yellow stator a few days ago when I was Shooting something else so I thought that perhaps the stator that I swapped out was probably too weak. Then I put the original double yellow stator back in and I had the same results (everything works but all the electrical are weak). Then I connected the battery and everything is super bright, specially the headlight.

As you can see I have a list of things going on:

1) headlight very dim without the battery
2) All the electrical systems work with the battery disconnected

What do you guys think?. That never happened to me. At this point I don't think there is anything wrong with my stators.

It sounds to me like it is grounded out somewhere. Check all connections, switches and the area where the wires come out of the neck into the headset,

i think you should keep your battery hooked up so that your lights stay bright.

We don't usually have the double yellow stators here but if you haven't substituted the regulator with a good one, now's the time to try it.

On Scooterhelp's website they have a wiring diagram for your Vespa. One with a double yellow stator.

http://scooterhelp.com/electrics/pages/VSX1T.p200.html#before

So the rectifier is what's keeping the lights dim. It charges the battery but doesn't have a lot of amperage behind it.

I remember reading something on the forum that you shouldn't run without a battery as it'll burn up the internals of the regulator/rectifier. Never confirmed it but just remember that useless fact.

That said, why is your headlight dimming as well? I'd guess a worn/cooked regulator. Swap it and see if that fixes your headlight.