How to wire a Lambretta 12 volt conversion
The best set up for a Lambretta is a modern 12v CDI system, but that generally requires a new GP flywheel and crankshaft. However, you can easily change a standard 6v Lambretta to 12v wiring and get better lighting. If you keep the regular coils, though, you won't get enough power. Change the coils to ones specifically wired for 12v and you'll be much happier with the result.
To make the change, you will need our 12v stator coils and regulator, and can then add 12 volt bulbs. We highly recommend a halogen bulb. You should also change to a new Vespa coil. These items are found in the Lambretta Electrical and Lighting sections.
If you have an old junction box, remove it. Use the following diagram to wire the stator with no battery when you add the coils we sell.
The black wire goes to ground, and the blue/green is unchanged.
The red wire will go to the regulator, which you can mount above the rear mudguard. With the plastic part facing down, the left side has two prongs. Either one is fine to plug into. (If you have a CDI system, another red wire will come to it, otherwise nothing.) On the right side is only one prong and it goes to ground.
By the way, your horn is 6v, but will work at 12v.