$0 Vespa 12V Conversion with Stock Electrical Parts

Basically just a split phase A/C power source. The two different coils are 180* out in terms of phase angle since the coils are physically 90* apart from each other and there are 4 magnets in the flywheel. This gives us two coils with a 180* phase angle relative to each other.

I hooked my grande up this way today and it puts out about 20v unloaded at mid range throttle, so I installed a regulator and am waiting for the rain to die down. My system was 12v before with a single replacement 12v coil.

A dual coil system like this is ideal as compared to a single coil 12v coil with twice the winding. The reason being that a dual coil system like this will be a higher power output since it has sufficient turns to generate 12v while maintaining a larger winding gauge than a single 12v replacement coil.

Here's the wiring diagram if you still don't get it. If you find you still have 6VAC, swap the turn signal lead you have connected to the light coil lead. You can change the phase alignment by which wire is connected from the turn signal coil to the light coil.  You need them with the hot wires connected opposing to get 12VAC. If a hot and ground are connected between the two coils, you'll just get a higher amp draw 6v coil.