Sunday, March 15, 2009

Vespa Ciao wiring repair

I'm doing some minor repairs on a 1976 Vespa Ciao, which is a cool little 50cc moped. I was quite happy to find out about Zippy Moped, who stock a lot of parts for the Ciao.

The wiring on this Ciao had deteriorated over the years and showed some poor-quality repairs. One of the previous owners also lost the bracket that hangs over the engine and holds the foot rest cover and, I suspect, keeps the wiring away from the hot engine casing.

Here's what I've learned about Vespa Ciao wiring so far:
  • the electrical system is 6V AC. Don't forget to put your multimeter in AC voltage mode before measuring since you normally use DC. For example, I wanted to know if the ignition feeder coil and condenser circuit were actually pulling 6V across the ignition coil so I disconnected the coil and measured the voltage (with respect to the engine casing) while pedalling.
  • electricity is generated by a magneto that consists of the flywheel, which has magnets on the inside, and two 'feeder' coils that sit underneath it. One coil is for the 'lighting' circuit (front and rear lights, horn) and the other connects to the ignition coil through a condenser. The main shaft that the flywheel spins on actuates the ignition points, which can be adjusted through a little window that's normally closed off by a rubber cover.
  • the wiring is really simple but not very robust: a burnt-out tail light can be enough to kill the ignition and putting a 12V bulb in the tail light (as was done by some previous owner) is really bad. If in doubt, unplug both brake light switches from the handle bars and, on each one, short their two leads together to bypass the tail light entirely. The correct 6V bulb is available.
  • near the engine, in general, the ignition wiring is purple and the lighting wiring is blue. There's a red wire which is the lighting circuit ground and a black wire which is the ignition circuit ground. There are several wiring diagrams available but none of them seemed to match this Ciao and that seems to be fairly normal.
  • You need a special tool to remove the flywheel, and you need to do that to get to the 'feeder' coils and condenser. It's not very expensive and you can get it from Zippy Moped Parts.
  • The clutch mechanism has two sets of shoes, one of which is only used for starting the engine. The engine should start easily with the decompression lever pressed, mine doesn't and the starting shoes do look worn. It does start when I pedal a little, so I think it needs new starting shoes.
Beside wiring repairs, I wound up installing a missing bracket and decompression cable, air filter, and fuel filter. I also replaced a broken carburetor elbow piece for the throttle cable. The Ciao now runs pretty well (and reliably) but the carburetor needs adjustment and I need to fix a fuel leak that I accidentally caused while replacing the fuel filter.


John said...

how did you put the flywheel back on? mine doesn't seem to want to sit right - it breaks through the woodruff key

John said...

instructions would be helpful - what is the size of the woodruff key?

andrey said...

You just slide it back onto the main shaft and it'll press itself back in when you bolt on the clutch in the end.

Anonymous said...

where did you find the bracket (that protects the wires, and for footrest mounting)? i can't seem to track it down.

andrey said...

I bought it from Zippy Moped parts:

Anonymous said...

When I start pedalling, should the tail lights start to go on too?

Andrey Yurovsky said...

Yes, they should. The headlight has a switch but the tail light should always be illuminated if there's power. It uses an odd 6V bulb as I recall.

Anonymous said...

Got new bulbs, and my head light, tail light and brake light all illuminate. Still not starting tho.

I pulled my sprk plug out and ran it to see for spark and I can't see any.

Bluebravo78 said...

Can you take a look at my bravo magneto and help me please. I have no idea where the green wire (brake light/ignition ground) goes. Any help appreciated.,3108183,3108312#msg-3108312

Daniel Sterling said...

Hello, Nice work on your Ciao. I have a question if you have time. I have a 73 Ciao with some wiring problems.
I have one wire(with 2 wires for brake/tail light) and one wire that has a gray sheath and a single white wire(which has been cut) both going through the frame towards the rear of the bike under the rear fender.
I cant figure out what the white wire goes to, do you have it and can you tell me what its for? Thanks

HN said...

how is yr kill switch wired up? From the engine, I have two wires that i know go into it for sure but there's also a extra spot for another wire on the kill side. Any help?