I have a B31 1957 (alternator model) in bits, and I am trying to reconnect the alternator and all the other wires on the old harness. (It's in reasonable condition so I haven't replaced it.) I photographed all the connections before I took it to bits, but the alternator photo is not clear enough to tell which colour goes to which.
The three wires coming out the alternator are one brown (ish) and two white (ish). The three wires on the harness are black, dark green, and a kind of light green. None of these corresponds with the BSA Service Sheet 808H (attached) which is the only one I have been able to find with an alternator.
Any help and suggestions are most welcome!
This may assist.
The first photo is the wiring diagram from the alternator B31 owners manual.
Lucas changed the colours of the alternator cables because the colours on the earlier ones tended to fade. The second photo shows the transition of colours over the years.
The last photo shows the internal alternator connections with the later cable colours.
The challenge is identifying which of your colours match the Lucas ones.
Thanks Julian. Amazing where you find this stuff. I have the first diagram, but the second one may help me connect what I have to the harness. I suspect someone has rewired the stator with their own colours at some stage. There ar quite a lot of non-standard things on this bike...