Model 50 6v to 12v Conversion

've read that the Alternator just requires a wiring change. Is this true or should I buy a new Alternator ?

Keep your old alternator, it pumps out unregulated AC at voltages up to and beyond 50V when pushed

I know I need a new Battery & Bulbs. Do I need a new Ignition Coil and Rectifier ?

Yes new coil or fit a ballast resistor, rectifier stays

Do I need a new Ameter ? (No details visible of how this is connected in on the wiring diagram I have).

No but the range on the 12v ones is higher for the higher output but in practise not a problem

Can I retain the existing Lighting & Ignition Switch ?

Yes

Do I need a new Horn ?

No as long as you do not use it a lot, and lots of short presses not one big one

I assume I can retain the Contact Breaker Unit but will it need a new Capacitor ?

No

Any pitfalls I need to be wary of ?

You will need a voltage regulator, a zener or a modern combined rect/reg is the same price.

See attached info sheet courtesy of Al Oz. It is a bit old but should be ok for the whiz bang bits and wiring suggested. If not sure give him a call.

Other diagram shows a similar conversion but in very basic form for 2 and 3 wire alternators.

I would always recommend that the zener and rectifier be changed for a 12v electronic regulator. The wiring is simpler plus you generally get better reliability and less voltage loss. Regulators usually cost less than a new zener and Lucas type rectifier.

When I converted from 6 to 12v I had to change my old horn as it started to make strange noises and cook the wiring when used. however, that may be due to its age or my poor wiring.

Attachments
3%20Wire%20to%202%20Wire%2012v%20Conversion.bmp
al-oz-12-volt-conversion-jpg

"Somewhere on this site I assume there is a write-up on making this conversion, but I have been unable to find it."

On this site, if you find your way to:-

Technical / Electrical / 6V to 12V Alternator Conversion

Here there is a very useful write up.

Regards, Alan

Go to http://www.nortonownersclub.org/roadholder

RH is for roadholder, the number is the issue, note that not all are available