Fellow readers,
Can someone explain what is the use of a dip switch and whether WD motorcycles had one?
Should I start looking for one for my 1940 Norton WD16H? 
Kostas
email (option): ferrarakias@hotmail.com
Thank you both gentlemen!
A picture would be great Lex, thank you. 
email (option): ferrarakias@hotmail.com
Thanks Lex...I wasn't 100% confident that early bikes didn't have them when I made the posting...should have mentioned that fact really....Ian
email (option): ian@wright52.plus.com
Well thanks to Lex I found out that I should have an early type dipswitch mounted on my handlebar. If anyone has such a dipswitch for sale please let me know.
That's what I'm after...
email (option): ferrarakias@hotmail.com
It's a race then Kostas. I'm also looking for one to mount on the back of my pre war BSA levers....Also the matching horn button for the other side.
Maybe i'll find two at Stafford???? Ron
email (option): ronpier@talk21.com
I'm sure I will end last in this race Ron!
THIS is the switch we are after
email (option): ferrarakias@hotmail.com
We need a British american dictionary.
British American
Dip Switch Dimmer switch
mudguard Fender
Headlamp Headlight
Petrol tank gas tank
And don't get me started on;-
Flashlight
Hood
Trunk
Aluminium
and Tomato pronounced Toe-made-oh
Ron
email (option): ronpier@talk21.com
potarto potato lets call the whole thing off
Hi Kostas and Ron.
31563, no problem, in stock. 31340 (which screws to the back of BSA levers) are out of stock. I have ordered from the states, so hopefully in soon. Kostas, the switch in the pics of my Norton I sent you has just been reproduced and should be available soon.
Thanks for the pic Lex.
Cheers, Mick.
email (option): mick@motorbikemike.org.uk
Kostas, I think that you need to investigate a little before deciding that you should have a dip switch screwed directly to the bars. I've been down that route !
My C5109 bike definitely had dipswitch wiring but unfortunately had lost the switch. Period photographs are unclear but I can only find evidence of the screw-on switch when fitted to pre-war contracts together with the combination levers (air / AR levers forming the top half to horizontally split lever clamps).
The threaded holes seem to have been provided on all 1" WD16H bars, even though the switches had long been discontinued. If you measure the location, not only are they rather oddly on the rear of the bars but they are only 6 1/2" in from the end and on bars with separate levers such as yours (and mine) this leaves little space for the clutch lever bracket, valve lifter and A/R control.
Period pictures seem to show as you'd expect that the more important controls were outside of the dip switch. Valve lifter must be accessible from the grip and preferably the ignition control as well.
The type of switch used on the back of BSA lever clamps doesn't fit exactly as the BSA clamps have a raised flattened section with a greater radius than the Norton handlebar.
I have used the same type of switch as Mick. These certainly saw wartime use prior to the dipswitch being discontinued. They were quite easy to find until fairly recently (with modern cable) as they were used at least up until 1975 to operate the blue lamps and two-tone horns on Norton Commando Interpols (and probably Triumph Saints as well).
The clamp on switches have the advantage that they can be positioned to suit the rider. They are certainly 'period' but I haven't yet been able to establish if they were a factory fitment during 1940.