Modern Vespa

Longtime lurker. First post. Lambretta nerd seeking Vespa knowledge.

I have a US-market 1966 SS180 with a Siem 'Mickey Mouse' tail light and looking for a wiring loom. It's a Mk2 SS180 so AC. I don't have an existing loom for reference but believe (happy to be corrected!) the brake and running lights share a common ground and not individual circuits as per the regular, Siem tail light.

Is anyone remaking looms for these models? Or is there a specific 'Mickey Mouse' wiring diagram available? Thanks!

I don't have a 180ss diagram, but here is a smallstate diagram for the mickey mouse tail light.
3 wires in, running light, brake light and ground.
Sorry couldn't be more help.

Lots of loom options.

But... need to confirm ... non battery bike?

https://www.scooterhelp.com/electrics/pages/VSC1T.180ss.html#nobatt


From there you can grab a loom off Scooter Mercato or SIP.
Non battery:
https://www.sip-scootershop.com/en/product/wiring-loom-092653-for-vespa-vbb2t_87001100?usrc=wiring%20loom

With Battery:
https://www.sip-scootershop.com/en/product/wiring-loom-092653001-for-vespa-180-ss-0024701_87001800?usrc=wiring%20loom

Ground is ground. The fixture should (or could) be grounded to the frame. You don't need a special loom with a black wire.

The original US SS180 harness is unique. Usually they came with no pilot light in the headset. I have not seen the exact correct harness available anywhere. The closest harness off the shelve that I know of would be a VBB non battery harness. It could be used with very slight modification.

I remember better now. They are more different than I thought.

Check this out. I'm not sure a VBB non battery harness will work.

https://vesparestoration.blogspot.com/2008/04/wiring.html

You may have to make one from scratch to match the original.

That is very good.
Jedi, I read your post too quickly and missed the part abut needing a whole new harness? Still, there is nothing tricky about the MM light. Virtually any fixture should use the same two wires plus ground. All grounds are common.

Thank you! That answers a bunch of questions I had. Thank you. Yes, as above, it's a Mk2 SS180, so AC electrics. Thank you, this is EXTREMELY helpful! By pilot light, do you mean headset gem—as per Rally 180/200 and many other '70s largeframes? I'm not sure about the really late US-market SS180s with round headlights, but this is trapezoid headset as fitted to SS/GL/Sprint/Mk2 Super and has a BA15s socket in the SIEM bulb holder for a parking / daytime running light.

Yes. The small bulb above the headlight bulb is the pilot. My '66 SS is literally parked in the next room in my house.

That is interesting. I have rebuilt 5 US spec SS180s. All factory white with trap headlights and mouse tail lights and non of them had a pilot light in the headset. Only a speedo bulb and a 25w high/low standard headlight bulb.

I know the euro versions had a pilot bulb incorporated in the SEIM headlight reflector. Those are what I have seen as a standard repro currently available. I have never seen the original US headlight reflector base/bulb holder units available as a repro.

I believe the stator coils and the harness are also unique.

I have no idea why Piaggio changed that for the US market. Like most unique US spec parts, availability is very limited.

If you ever have to replace parts of that elec. system, you might have to make the harness or rewind the coils to match the originals or you could switch to the standard euro non battery system that would be something like a VBB system. In that case a euro headlight reflector base would allow you to balance the system and have pilot light in the headset. Then it would basically be a VBB non battery sytem.

I checked the headlight and I clearly used a repro ( Elma) assembly with a pilot. I do not remember the original. The diagram (No Bat) on Scooterhelp shows a pilot tied with the speedo bulb. It also looks exactly like the VBB harness.

I don't think that wiring diagram applies to US spec SS180s. I believe the US system is pretty different. Scooterhelp's diagram is misleading.

I think that shows a European non battery system which is the same as a VBB.

I am curious to know how.

Same.

The easiest way to describe it is to look at the link I posted earlier.

Different coils and harness. 4 wires off stator vs the VBB 5.

The the coils and wires have to change if you remove the pilot bulb from the headlight.

Does that help?

IIRC, I have an OG US market loom... will dig it out and see.
Even if it is different than the current Grabor loom offerings, I can't imagine a situation where it couldn't easily be modified to work.

I pulled the juction box cover off and this is what I find.
Four wires from stator: Red, Green, Black, and Blue. One of the Reds going to coil.
Five from loom: Red, Green, Black, Blue, and two Yellows.
For some reason, I tied the two Yellows together but they are not connected in junction box.
This was a few years ago and I honestly don't know why I did it this way and everything works as it should. May be a VBB harness ?

Yes, anything can be modified to work.

The point is that the original system is unique and the known wiring diagrams are wrong or misapplied to many if not most of the US spec. SS180s.

That is what is causing all the confusion.

This has been known for a while but there are so few US spec. SS's that this info is not widely known, even here.

I'm just relaying what I have seen.

I'd have to pop the switch to see why I connected the yellows. I think the green is supplying power and the blue is just the brake.
Did all the US '66s have the MM tail light? Was it offered in Europe? Mine, which I am confident was all original when I got it, didn't.

All the 66's I have seen had the MM tail light, trap headset and were Hawthorn white.

I have no idea if they ALL had MM tail lights but I would guess the US spec ones typically did.

I'm sure many have been modified over the last 50 years too.

I believe the Euro models had the standard chrome tail light and came either with or without a battery system based on the country of destination's law requirements. Both being different than the US spec ones.

Mine was Hawthorn White (plus a couple of other shades of white) but I decided it had to be Pavone Blue. Knockout color! My '66 Allstate 125 has the MM light and is Hawthorn White, which was the only color offered in US. Canada got red.

So, the "1966" U.S. models (Including / typically Sears) have no yellow wire from the stator, no parking light, and a two position light switch (95041 iirc). The white and yellow wires connect at the light switch. Look at a bluebadge Sprint /smallstate diagram. The MM VA15T also is the same. The brake light coil is the difference, it's got no yellow wire to the harness.

Hope that helps.

Correct. Nicely stated.