8 hours ago, atitagain said:

Thanks for the help guys.

Next up, I seem to have just a coil and the 3 wires from the engine. I'm not have lights at this stage and when I do I'll go for an Electrex kit. At this stage I just want to assess a running engine. The coil was in a back with a black block connector, which wire goes where? or a photo if anyone has one. 

The LT ignition wiring from the magneto to the HT coil is usually black coloured. The other wires from the magneto are for lighting and should be insulated from each other and the frame. It doesn't matter how you make the connection for the LT ignition wiring as long as it is secure and electrically insulated from the frame. Bultacos usually have a wiring connector strip near the front downtube but using it is optional.

One wire from the kill switch connects to the LT ignition wire. The other kill switch wire connects to the bike earth (frame/motor/stator plate)

Edited January 28, 20233 yr by feetupfun

"3 wires from the engine" - what are the colours of these ?

I'm assuming red, green and yellow. If this is the case, the  black?  wire from the HT coil should be connected to the red. Green (originally feed to stoplamp switch) needs to be connected to a reliable earth. Yellow you can insulate and ignore - this is the wire from the lighting coil. This applies to the original Femsa wiring.............which may have been altered in the last 50 years.

The foregoing  is simply to provide a spark and get the engine running. HTH

Edited January 28, 20233 yr by lorenzo

Hi, I have black, yellow, green. They look original to me. The green in the photo is not connected to anything. The black and yellow are earthed at the same point? The black from the magneto is connected to the block connector, no spark but I'm guessing one of the wires are wrong. This is a temporary bodge just until I know the correct setup then I'll clean it up but the earth is clean and good.

Edited January 28, 20233 yr by atitagain

I've re-read the post and earthed the green, now I have a spark. I'll buy a kill switch now.

You have a spark - good, you're getting somewhere.

Wires in the pic. appear to me green, yellow, and black with a white tracer - in which case, not original.

Yellow is normally connected to lighting coil. Is the lighting coil present ?

Hi Lorenzo, the wire is just black, it's the light making it seem there is a white tracer. 

No I don't have the lighting coil. I'm not sure if I will fit lights but if I do I'll use the Elextrex unit 

Any idea what this is? it came in a bag full of spares

Sherpas have three or four wires coming from the magneto. Green goes to earth, Black goes to the coil and kill switch, yellow is lights so just terminate that at your junction box. Some later ones have a red wire also which is also stopped at the junction box.