BSA 1960 Spitfire Scrambler Wiring Query

[Superarnie]

Good evening chaps and chapesses,

I am currently restoring a BSA A10 Spitfire Scrambler. Mine is a 1960 model with a 6v dynamo fitted. Being a scrambler, that model didn't come with lights/horn etc, but a previous owner installed an ignition switch, battery and lights and horn and a dimmer switch mounted on the handlebars.

As part of my restoration, I am upgrading the dynamo armature to 12v system. I have purchased a DVR2 (positive earth) regulator, a new Lucas harness/loom, a new battery, a new dimmer switch and a Thorspark electronic ignition system.

It may be worth advising you all that I have a very basic knowledge of vehicle electrical systems.

When trying to install the electrical components, every wiring diagram i have found, incorporates an Ammeter. My bike will not have an ammeter installed.

As it stands at the moment, with regards to the light circuit,  I have a brown wire coming out of the regulator which I think will connect to a purple wire in the new loom(?) That purple wire travels to the headstock area. I am planning to run that wire to a on/off light switch (circumventing an ammetre). From the 'on' position of the light switch, send a wire to the dimmer switch and 2 wires from there to the head light (hi and low beam). Can anyone advise if that would be alright.

Secondly, I am considering a fuse and relay in that circuit. Would that be the general consensus here and if so, would the fuse go between the brown wire from the regulator and the purple feed wire as described above?

If anyone could attach a rough schematic, I'd be very grateful.

Kind regards

Gary

[Spaceman]

If you don't fit the ammeter, all you have to do is to join the wires together that connected to either side of the ammeter.

The normal place for a fuse is between the battery supply terminal (the opposite to the earthed terminal) and the rest of the electrical harness. That is because the main danger is from the battery being shorted out.

It would be interesting to know which new loom you have purchased and whether you have the wiring diagram for it. If the only thing you are missing is an ammeter, that would only require a very simple mod to the wiring as suggested?

[Superarnie]

Thanks Spaceman, I thought that might be the case. The Lucas loom was part number 839780. It came with a very rudimentary wiring diagram; it was basically a branch diagram showing what component the branch ends connected to.
Thanks again.

[Spaceman]

If memory serves me, there was a post recently concerning new wiring looms for the A10. Part of the issue was whether they were designed for a -ve earth or +ve earth system and there was also an issue with the colour coding of the wiring. I've got to dash out in a minute but it may be worth a search to find the previous post so that you can check what you've got against the problem loom that the previous person had bought.

[Spaceman]

Try reading this to see if it's relevant:

https://www.bsaownersclub.co.uk/bsaoc_forum/index.php?topic=15385.0

[Spaceman]

Just got back and read the previous post - looks like you have bought the same Lucas wiring loom as this member had problems with so worth reading what was said on the issue!