Modern Vespa

There is a five wire bundle that comes to the junction box on the engine from under the seat. It has black, red, yellow, purple, and green wires in it. The green (only) wire on my P200E was fried looking and crumbling so I started dissecting the black tube covering from the junction box end looking for sound insulation. My plan was to cut off the bad wire and splice on a new green and recover it all with heat shrink. Long story short, the green insulation and wire was crumbling all the way to the place where the bundle came through the frame wall.

My questions:

Is this bundle a single bundle all the way to the horn cast junction box?

What does this green wire power? (It is the right hand green wire on the CDI unit.)

Can I just replace what I have and trust to the remailing wire, or must I replace all the way to the horn cast junction? In that case I would just run a wire parallel to the existing bundle. (No a new harness ain't happ'nin.)

green wire runs from your CDI up to any kill switches on the bike ...so, your keyed ignition, and your run / kill switch on the handlebar.

That's a bad wire to fray, because if it grounds to the inside of the frame you won't have spark.

It's easy in the sense that you COULD pull a whole new single wire through your bike, though, from junction box up to your headset ...and make it work easily.

Damn! I was afraid you would say that.

Try to get the same wire type and gauge. These bikes are fussy over small details.

I would of course use the same or larger gauge.

When I went to the junction box at the horn cast I found that the green wire there looks bad too. Not as bad and I am trying to disrupt it as little as possible. All the other wire looks fine.

It's obvious, they just got a really bad batch of green wire. There is no info printed on the wire so the nature of the insulation and manufacturer is hidden. Since wiring harnesses are routinly provided by outside manufacturers I would say that Piaggio's supplier went with some sub-standard wire when they needed some green. I am sure this was intentional on the suppliers part, and Piaggio didn't catch it on incoming QC. 1980 was well before ISO 9000 and all that good stuff. Wonder how much of their wiring Airbus got from Italian suppliers? Piaggo also makes aircraft!

Maybe it gets hotter and more prone to degradation/moisture.