Modern Vespa

So I have a Ducati regulator, with the two G connectors. Unregulated AC in and regulated AC out. I'm getting intermittent voltage spikes that blow the headlamp bulb. I'm not using the sealed beam thank goodness. I have a 12v AC regulator, and since everything else works, I'm installing it in the purple circuit under the horn cover. Question is, can I leave the wires connected through the regulator G connections and let the inline regulator up front handle the spikes, or pull the wires off the G connections and splice them, isolating the Ducati? Any downside I'm missing to either route? Thanks. I don't have a known good replacement. Pics of the newest addition, built from pile O' parts.

Are you still using a battery? If so, the two yellows will need to be in the Ducati reg to charge that. I can't think of a problem adding another regulator to it. Unless it doesn't charge the battery/ totally stop letting AC power through/ weak output.

Scooterwest does have some pricy replacements that I've had success with if you just want a direct swap.

Yep, still have battery. Seems to be charging. I couldn't think of a reason not to have two, but I've thought a lot of things that were erroneous. Thanks for the tip on SW, I'm just a few miles from Scooter Mercato. I'll check there too. I'm traveling for work Monday through Wednesday and trying to slot one more ride in.

The last few I dealt with the AC voltage completely died or were dim. Bashed my head in checking headlight wiring when it was an intermittent fault at the Ducati regulator. New scooterwest one did the trick. I think it's some off road Baja moto company regulator that Robots adapted to the old layout.

Thanks MJ!

Correct me if I am wrong, if you have a double G (double yellow) system, which uses the 4-pole regulator/rectifier you are showing, the purple wire from the stator is not regulated. It goes straight to the headlight. Two separate AC systems there; one to charge the battery, one to power the headlight. Yellow-yellow charges the battery, purple runs the headlight.

The newer (1980 on) red/yellow system with the 5-pole regulator has a headlight regulator as it uses a 'higher output' stator. It is the A-A purple leads into and out of the regulator/rectifier. Similar to the earlier system, it has two separate AC systems; red-yellow charges the battery, purple runs the headlight.

You can run a separate 12V AC regulator under the horncast to alleviate your headlight burning out. If you run high rpms, the headlamp will burn out on the older yellow-yellow system as there is no regulator on the headlight circuit. Higher rpms = higher voltage, leading to burned out bulb.

You can also run a higher wattage bulb to take more of the load. It will be a tad dimmer at idle and lower speeds. Stock spec is a 30watt bulb. I run a 35watt without a regulator and have not burned out a headlamp in years whereas the 30watt would burn out quite frequently, especially if rpms were held high for awhile.

Good catch, I did take a pic of the wrong regulator! It's the newer system. So far I still have a light, so seems to work ok. I used the yellow/brown wire cheapo regulator like the one on my VBA.