Hello my bike is 12v +ve earth with magneto and 2 wire alternator, zener diode and little 4 prong solid state rectifier Wiring is bit of a mess but all works ammeter indicates a charge There is no ignition key just a mag kill switch. Big bakelite keyless knob on headlamp for lights. Will i be able to source a new wiring loom for this that will need modifications? Thanks
Suitable looms are availiable , I thought them too flimsy and decided to repair the orriginal (which is still in use) . I would fit an extra earth wire up to the headlight shell and a good heat sink to both Zener and rectifier . I also run with the pilot on to keep the zener load down.
I think all bikes (especially 6 volts like my two Nortons!) should have dedicated earth wires to its extremities. Tail lights and headlight. Use a domestic, nickel-plated earth terminal block behind the battery box or somewhere close to the battery, but out of sight. Take a fat earth cable to it and then run the cables wherever you can.
The distributor could benefit as well as the horn but the lights especially will be better without resistance losses due to weathered contacts and terminals.
You don't say what year what model? Of course knowing such and quoting to wiring company might give you trouble if the bike is supposed to have coil ignition.
I can offer you an alternative, I sell a wiring kit for alternator bikes, so you just rewire what you have in your way. While you are modifying a loom you can have wired the bike properly. Also a Magneto with a Zener diode is an unsafe situation-facts are on my web site aoservices.co.uk 12V Alternator and magneto-how not to do it. As well as the loom kit I can help you with any specific problems you run into.