.... and here's my £4 Heath-Robinson offering! Ash, can you verify the wiring diagram ok pls...
1st up you'll need to take your junk drawer 'Field Coil Voltage Regulator', make sure its ok and then do minor surgery to it. Don't have one in my hand, and I wouldn't think hard... esp given your trade.
There's a live in (black connector), an earth (Green) and a white.... whose output will be in accordance with the points position. What you need to do Mjc is organise that white to be open circuit normally (points UP) and black wire (ie loom) voltage when points switch to the down position.
Then, from Maplins buy a £4 12v/15A minimum SPDT relay.
eg
http://www.maplin.co.uk/p/12v-30a-dc-spdt-automotive-relay-n00awThe plan is to use your modified regulator to switch this relay when voltage exceeds 14.5, and in doing so short the PMG yellow field coil to ground.
Wiring diagram might be as below...
Good luck.... like Ash's suggestions of using the correct bits... but then where's the fun / challenge!
As for the loom, personally given any you buy is gonna be 40yrs+, your experience.... and that your bike is not planned to be original in terms of wiring I'd be tempted to make up a shiny new loom.
I've not done one myself, but the Internet would be a great place to start. My reckoning would be to design your circuit on paper, and install all the electrical bits onto the bike. Then, and one at a time, install each circuit onto the frame, tie wrapping the wires to the bike as you go. As new circuit adds on, tie wrap the new wires to the building loom. Leave all ends with a surplus 20cms or so. Once the loom is complete, cut it away from the bike, insulate all the soldered connections you'll have made, and then tape the whole thing up soundly, cutting the binding tie wraps as you go.
Reinstall it onto the bike & now cut the ends to length & terminate. Just a thought...
These guys have all the wiring, connectors, heat shrink tubing, heat resistant sleeving yada yad that you might require.
http://www.autoelectricsupplies.co.uk/product/70Batteries... Lithium etc...
http://www.carrotcycles.co.uk/index.php?_a=category&cat_id=217Cost a small fortune, and VERY technical in terms of charging / discharging. They need very specific chargers... ie you can't just bung in 14.5V and not expect something terrible to happen. Honestly.
Carrot Batteries sell lithium types for 'bikes... and within the battery is the circuitry to adapt 40 year old technology to be compatible with the battery. This said, certainly in the short term, given your charging circuit is in its infancy / unproven can I suggest you steer clear of fancy LiPos LiFes & the like and so save yourself big bucks or worse, a burned out bike. One step at a time without wanting to sound rude!
Anyways, good luck with it all, the bike looks great..
Simon
(PS - Ash, any reason why the 'spare' yellow rectifier lead can't be connected to the LH Yellow & 'share' the load?)
