Vespa 50n Wiring Trouble

Hi all,

Sorry to jump straight in asking for help on my first post. [:$]

I've just had a nut and bolt rebuild on my 1969 Vespa 50n, 6v standard electrics. Tonight I put all the bulbs in. The headlight came on and then blew (possibly when I tried the horn, the horn didn't work), the side light, rear light and brake light work (brake light is very dim though when the other lights are on) and the horn will not work while the lights are on but when you turn them off it's fine.

Once the headlight had blow it measured 20v at the headlight terminal and 4.5v at the side light. I ran out of time to go through everything.

It also took ages to start up tonight once all the bulbs are in, when I've been starting it without bulbs it's been 1 or 2 kicks.

Any ideas where's best to start looking tomorrow? [:S]



I've just measured the voltage with the loom disconnected at the junction box:

Green - 22-24V

Yellow - 13V

Red - 12V


I guess all my coils are knackered?

I forgot to add the engine has a 90 kit on it.


Hi dude


Please check all the coils on your stator plate, i guess there is a problem.




Hi dude


one last question, maybe i understood wrong.

Do you have a 6 or a 12 V ignition ?




Thanks, I'll try that first.

I may even just go for a Vespatronic kit to prevent all future problems that come with a 6v system.

With a Vespatronic kit do I just need to change the light switch & rear brake switch (for one thats normally open / closes with the brake is used) & bulbs obviously?? Also can the existing loom be used & if so does it require any mod's??


Thanks Again.

It's a 6v system, thanks.



I've checked, cleaned & measured all the earth/grounds. Ok
Checked the wiring again & again, thats fine.
I've now put all 12v bulbs in & the horn now works with the lights. But now the head light, side light & rear light all come on together (with the headlight switch) & the side light switch does nothing.

To say this is pissing me off is an understatment >:(

It's looking like a daylight MOT is the only way to get on the road until I can sort this out. :-/

Electrics were fine(ish) on the MOT but it bloody failed on a rear shock >:( >:(

I've just order new front & rear shocks, the front one was a bit to soft for me.

Also order a Vespatronic kit, 12v horn, 12v conversion light switch, px rear brake switch, a Polini exhaust & new 12v bulbs of course.

Using the existing 6v loom with the Vespatronic kit can anyone give me any points on altering the loom?

I've read a thread somewhere about just re-routing 2 single wires the brake light switch & to the horn I think, but I can't find it now. :-/