EL004 ELECTRICAL

I recently acquired a 1959 Venom which had been converted to coil ignition (Boyer Bransden)as well as 12 v electrics. A 12v battery is fitted together with a Dynamo Regulator (V-Reg) from A O Services The bike starts OK ( eventually - still have not developed the correct precise knack) and runs OK. However, the Dynamo shows a mild discharge on running, a 5amp discharge with the lights on - whether running or not and eventually the battery discharges. I have to assume the wiring is OK and that it is the Dynamo that is not doing it's stuff. It is a 6v Lucas E3LM-LO , with 20013 and 6v -> 11 54 on the side casing.( OK I know I should have a 12v Dynamo ) but I have forgotten how to check that the Dynamo is actually working - by turning it into for a very brief time, an electric motor using a battery. Can anyone help? - Steve Bland 20/11/2001

You are right to start by checking the dynamo 'motors', and that when it does, it motors anticlockwise.....
If it was an original Lucas dynamo using a mechanical regulator, you just put 6v through the D and F connections (having disconnected them from their normal connections to the wiring harness if the dynamo is still on the bike: or after connecting the battery earth to the dynamo body if on the bench). You might have +ve or -ve earth, but whatever your earth, keep it that way, and connect a wire from a 6v battery terminal to the D & F terminals on the dynamo. It should motor smartly in the same direction in which it is normally driven.
However, your dynamo's wiring will probably have been modified in conjunction with your conversion to your electronic regulator, with which I have no experience. To do the motoring test on a dynamo whose wiring has been changed to suit a JG electronic unit then, having disconnected the bike's wires from D and F, you connect a wire from the dynamo's F terminal to earth and connect the battery terminal to D. (And if the dynamo isn't on the bike you'll need a wire from the normal earth terminal of the battery to the body of the dynamo.) It should then motor, but if it goes round in the opposite direction to when driven by the engine the two field coil leads need their connections reversing. I guess all electronic regulators probably make similar wiring changes in the dynamo, so their motoring test would be similar. As long as you've completely disconnected the electronic regular before you do the motoring test on the dynamo I don't think you can hurt anything. 
And you do have a 12v dynamo! - it's the electronic regulator and the battery that decides the voltage (through magic). I have two similar dynamos working perfectly at 12v using a JG regulator.
Anyway, try the motoring test, and if it doesn't work we'll work out why, though you must have a digital ohmeter - under £10 nowadays. - TW 20/11/2001