I recently purchased a 1951 BSA ZB3, that has had some fire damage but still is a running bike. The damage from the fire was all cosmetic. The question I have is on the light switch that is located on the headlight shell. The switch on this bike has positions for OFF, T, L, and H, and has 7 connections on back for the wiring. On this bike there was no Headlight dipper switch out by the handlebar grips. So,..I am assuming the positions on the switch relate to, OFF, T – Tail lights, L – Low beam, H - High Beam. Having the headlight dipper on the headlight shell is kind of an awkward place to have this. I have several manuals
and they cover many models so it’s difficult to determine what my particular model should have.
Most switches I see have 3 positions, Off, L, and H, and I am assuming this is Off, L – Lights-Tail/Parking, and H – Headlight (with the dipper out near the handlebar grips).
I am wondering if someone with more knowledge of the BSA switches on a 1951 ZB31 could tell me what the proper switch for this bike should be. Since this bike was a “Z” model, perhaps a 4 position switch was standard. Every wiring diagram I have seen so far however shows a separate dipper switch, so not sure what’s up with the 4 position switch currently on this bike.