Modern Vespa

I recently bought another Rally 200, and I am trying to understand the wiring of a 12v conversion they did. So, a 12v converted scooter has 12v AC coming off of the engine side. This goes to a regulator, and then the lights are run from this. Are these lights running off of 12 AC or DC current? Regardless, is there any type of electrical bridge I can put in the horn cast which will convert that current to 6v DC so the 6 v horn will work?

Short answer, no. I did a post on this years ago. There's not enough amperage in the AC voltage to power a 6V DC horn. Maybe now with small batteries you can buy on Amazon, you can fabricate something that hides in the horncast that'll work until it needs to be recharged.

I was successful getting a 6V AC moped horn to beep hidden behind the face place of a 6V DC horn. That was with the 6V femsa stator converted batteryless 12V. This was years ago and I think I've used the horn 2 times ever since then.

Great. Saved me some time for sure. One other question, my light switch on this 12v AC converted rally is stock, and works but not the same with the settings, I am assuming I need to put a different light switch on with the converted system and it will work the same as it does in the 6v dc version? And one other thing, are the lights working off of 12 v AC or 12 v DC after the current comes off of the rectifier? It is so confusing.

Not the same with the settings? I'm not following you there.

The US model DC harness and switches shouldn't have been messed with for a batteryless conversion. Just ground one yellow at the junction box and 12V+ AC comes out the other yellow. Hook that to a rectifier and out comes regulated 12V AC to whatever wires are connected to it.

Sadly everything was designed to work off the battery so when that went kaput, everything other than ignition went too. US P200s figured it out and just ran the headlight off AC and everything else DC which helped the battery in regards to demands vs charging.

If I'm assuming the system is correct, you should have a headlight, taillight and brake light. No horn, no turn signals. Is that not what you have currently?

Yes. Correct. However, the headlight switch - and running/brake light interactions on the right handlebar toggle switches are not working the way they originally did. Perhaps this is due to how it is wired to the back side of the switch problem I can trouble shoot? I will need to check this again in person when I get home, but there is some sort of weird set up where only at one position will headlight, running taillight and brake light all work properly as they did with original system. Any other setting gives one either no brake light or no headlight. Sort of odd.

On your system, does the front brake light switch work properly? Mine does not, but I do not want to replace it if that also does not work in these set-ups.

Thanks for the help, I believe I am getting closer to actually knowing exactly what is going on with this conversion.

I would much rather have these piddly problems with basically a solid bright headlight, than always fussing with that battery circuit which has always caused me endless headaches. I am excited because I have a 12v conversion set-up for my other Rally as well, and I can really appreciate how this should work so much better.

Can you post a pic of your headlight switch?

Okay. I attempted to get back of it for any wiring hints.

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One other question. Is it better to pre-mix gas with 2 cycle or use the oil injection system as intended with a newly bored out engine?

Switch is close, but not OG for a 74 US spec. Unfortunately you can't find replacements anywhere! It shouldn't go full blackout mode or one/ other like the 60s batteryless scooters. Probably wired up that way when it was covered to batteryless.

I don't have pics of the switches on mine but I'll try to get to my storage unit soon.

Back to your front brake, mine works because I have the OG lever with a little post screwed into it which activates the brake switch. Modern replacement levers don't have that so you would have to make one. The brake switch is on a little V shaped bracket that's screwed into the bottom of the headset if I remember correctly. Have that bracket and switch?

If the injection system works, use it. If it doesn't, premix. Only reason I'd say to use both would be if you had some stupid kit that required more than 2% mix.

There is something about the switch that is not right. When I have time, I'll look into the original on by other bike, and see what I can make work. If you have any specific suggestions, let me know. BTW. thanks again for your help, very grateful. !

That's a conversion switch. You can totally get that to work.
But it's wired currently like "what were they thinking"

You can grind off the back of the rivets that hold the cover and fit a zinc coated 12v AC horn behind it.

Thanks for the help. I was looking at the light switch on my other Rally and it is the same, except the wire colors do not match and they are going into different slots, so oh well.

I am going to get some pictures and diagrams and come back to this thread for some more guidance because I think I can figure this out, but I do not see any one diagram in any of my books or references that matches up to what I am seeing.

I will come back to this after a week or so, I have to tend to non Vespa business but I cannot thank you enough for the help!!!.