Modern Vespa

On a vintage ignition coil, where do the red (spark) and earth wires go?

One on the left and one on the right. Red and black wires if I remember correctly. It shouldn’t matter which way.

#3- Red/ Ground
#1 Black-power

It’s odd that they number the terminals 1 & 2 and the wires 3 & 6.

I am thinking the same. I don’t understand that diagram.

Yeah. Actually, the terminals on the coil are numbered 1+3. The wires in the diagram numbered 3+6 are the colors : black and red. The coil will work with the wires reversed but I believe it is more efficient wired correctly.

correct. to reverse it . . .it will run, but not very well.

I was looking at it on my phone. I can see now that there are numbers on the coil. Red and Black wires to terminals 1 & 3 on the coil.

^That’s for a bike with no brake light^

Normally black is ground.

The diagram below (for GL) shows black-ground to the #1 terminal, red-positive to #2.

Regardless, the colors don’t matter as long as the wiring is consistent and the circuit isn’t shorted.

I would say that it doesn’t even really matter as those old brown coils are 90% shit anyway. I have five or six of them sitting on my shelves collecting dust. I only use the 6 volt PX Piaggio blue ones for reliability. They work great with one red wire an HT cable.

Agreed. That's what I'm running on my SS as well.

Why they ignore the terminal numbers on the coil itself is beyond me...
OK, regardless of color : Terminal #3 on coil = Ground.
And yes, I had a brand new brown coil that's bad out of the box and went with a standard 6v metal one on the SS.

Yeah, I use the type that ground through the bracket. They seem to be more robust.

Oh Brother ! Wrong again.. I looked at the coil upside down as mounted and saw the 2 as a 3.... It is , in fact, labeled 1 and 2, which certainly makes more sense.
Maybe I had it backwards on the SS and that is why it would cut out after about 20 miles ??

Since this coil is used on an SS, I think I will go with the GL's wiring diagram: #1 is black = earth, and #2 is red = power. This colour (red) is the same colour as the wire going to the kill switch.

Yes that's the way.
I'm sorry, but I don't know how I screwed this up. On all the diagrams I can find that seem to use this coil, terminal #1 goes to ground. Except VS2-5 GS150 which do something different.

I use the simplest of rules for my VBB (and it's correct)...red on the rear.

http://web.archive.org/web/20060504233838/http://www.scooterwest.com/tech/wiringdiagram.html