1972 oif A65 wiring - blue/yellow wire?

[DiamondBeezer]

Hi All
Been running a 72 Lightning for 3 years or so.  It's a UK bike and pretty standard.  The indicators had been removed at some point and the switch replaced with an un-wired dip/main switch to match the other side of the handlebars!
I'm due to go to France for the MotoGP in May (unlikely now, I know...) so seemed a good time to retro-fit the indicators.
The wiring loom looks very stock and un-butchered.  Sourced a used handlebar switch on eBay and wired it into the loom. Ever wire matched perfectly for both handlebar switches, the (new) flasher unit under the seat and to connect to all four new indicators.  So I'm happy with the loom.

However, there's a blue/yellow (UY) wire coming up through the loom into the headlamp shell and connected to the rotary switch which turns the headlight on/off.  The other side of the switch is blue (U) and heads off to handlebar switch for dip/main.

Every single wiring diagram I can find on the internet e.g.http://www.motobrit.com/motc2/mphp/photopage.php?photo=/motc2/mimages/sch/bsaa6571sch.jpg&title=BSA%20A65%20(1971-1972) shows this wire should be brown/green (NG).  Every other occurrence of brown/green for pilot light, rear light, instrument lights matches the diagram.

So, finally, my question - can anyone identify what model wiring loom I have fitted to my bike with the blue/yellow wire to the rotary switch instead of brown/green?

Thanks
Ian

[ChrisG]

The OIF wiring set up is quite simple. The standard ignition switch incorporated a parking light which feeds the pilot and rear lamps.
The running with ignition and lights, last position on the switch, needs to include the headlamp or just pilot light facility so needs to have a separate feed that includes both. With the headlamp on, the pilot light also remains on. This is normal and how the designers intended.
So, the UY lead you mention goes to the rotary switch. If you want to run with lights but pilot and not headlamp (I would suggest this is unlikely unless you want to use the pilot with a High output/low wattage LED unit as a daytime running light) then turn off the headlamp at the rotary switch. Otherwise, just leave it be.
On my Thunderbolt, I can't remember ever turning the rotary switch to Headlamp off in 15 years of use.
Hope this helps!
Chris

[DiamondBeezer]

Thanks for the reply Chris.
Now you mention, I do recall seeing a UY connection on the 4-position switch.  Strange that every wiring diagram I can find show the W and NG wires providing the power and no sign of a UY.

So you start your bike with headlight already lit?  I've never fancied having say 75+Watts draining from the battery without the engine running to recharge it.  And I like all available battery power available to the ignition system when starting.  Or am I misunderstanding your rotary switch comment?

Cheers

Ian

[DAVE BRADY]

I generally leave my switch in the on position and there is no problem starting unless your battery is a bit flat or needs replacing.

Dave.

[ChrisG]

Ian,
No, I didn't start it with the lights on. I switched to position 1 (ign. no lights) to start. Then switch to Pos 2 (ign. and lights) when running.
To complicate matters, the barrel in the switch I had, didn't have the facility to take the key out of Pos minus-1 (parking lights) so no good to leave in the street with parking lights and the key in there. As such I disconnected that circuit from the switch.
By the way, I've seen many different wiring diagrams for models around that period and I've never seen one with UY either but the principle is the same.
Hope that clarifies.
Chris

[DiamondBeezer]

Hi Chris
Perfect clarification, thanks.
Think I'll stick with using key position 2 at all times and use the rotary switch for headlight on/off.
My key position -1 doesn't seem to do anything at all, certainly not a parking light, though it looks like it is connected to something.  I snagged a NOS LU35351 ignition switch on eBay last night (described as an indicator switch!) so will take a proper look at the connections when I fit that in a few days.
Cheers
Ian