12v conversion

[john11668]

Hi folks
Following on from this thread   http://classicmotorcycleforum.com/index.php?topic=5722.15   we are in the process of fitting a 12 v conversion.

Have fitted a new field coil and armature (12 v type) and a solid state regulator. https://www.ebay.co.uk/itm/Positive-earth-solid-state-DC-dynamo-12v-regulator-rectifier-Lucas-E3L-E3H/401549799839?hash=item5d7e3bb19f:g:mRwAAOSwrU1bG5ly:rk:1:pf:0

Trying to follow the instructions for the regulator which has wires for field and armature (yellow and green),  neg and positive (black and red)

The instructions are not clear on where to send the regulated output into the loom. The Bikes own wiring diagram shows a purple wire  to the ammeter with a brown returning to charge the  battery,  but we seem to have  yellow /green  and orange/ white . Tried both ways round with a protective fuse in place but the horn sounds so we are clearly bypassing the horn button. Otherwise confused !

My experience of old bikes  has been unfortunate as the wiring codes never seem to correspond with the book. Any help here will be appreciated 

[TGR90B]

I can only suggest that you enlist the help of someone  who knows motorcycle electrics John. I fear that you're unlikely to sort it all on a forum.

[john.k]

Simple....when in doubt,add more wires.......reg to ammeter,ammmeter to battery....(negative ,as it states pos earth.).....earth battery + to frame,or direct to dynamo casing..........have you motored the repaired dynamo.......is it correct rotation and polarity?

[iansoady]

Green is always connected to the field ("F" terminal) on the dynamo, yellow to the "D" terminal.

Those wire colours in the loom sound totally wrong to me. Essentially you need to take the live feed from the regulator to one side of the ammeter (and the feed for the lights etc are also connected here) and the battery live to the other. However, feed to the horn and stoplight switch are normally taken from the battery side so as not to give confusing ammeter readings.

You need to make sure the polarity of the dynamo corresponds to that of the battery. ISTR you're dealing with a 50s BSA in which case it's likely to be positive earth although swapping over isn't an issue.

I would buy some wire of the correct colours and rewire it. An easy afternoon's work. Trying to deal with previously bodged wiring is a nightmare.

Here's an example diagram:

[john11668]

I can only suggest that you enlist the help of someone  who knows motorcycle electrics John. I fear that you're unlikely to sort it all on a forum.

It looks as if I do have some constructive assisstance on this forum from Ian and John K.
I do have experience of old motorcycle electrics (and indeed old cars) but when your bike colour codes do not correspond with those shown on the wiring diagram it is natural to seek advice with regard to whether there may be a different diagram out there , (or if one is wrong then which is it)

[john11668]

Hi John K
Have indeed motored the dynamo and was correct rotation.
Will trace the wires to the ammeter and see what arrives there .  Will replace with Correct colours too so as to avoid future confusion . didnt want to mess with what was  in the loom though as I was unsure of whether there may be unseen  branch(es).

Ian
That is indeed the diagam I have and I have put the green /yellow in the right places ( replacing originals . one green/yellow wire and one which looks blue )
As you say a rewire  looks simpler than sorting out what is there . Will grab some black , brown and purple singles and a handful of pushfits .
Many thanks again(to both)

[TGR90B]

Sorry I spoke John. I'm glad to see you now have it well under control.