I am not 100% sure if it is a 6 or 12 volt,
What type of regulator and/or rectifier are fitted?
What voltage are the light bulbs?
What colour alternator wires go to the rectifier? And how many? Is there another alternator wire that goes directly to the ignition/lighting switch?
and when I connected a 12volt battery tonight, the positve lead got very hot soI took it off straight away. The wiring seems to check out against a wiring diagram I have.
Could you have connected the battery the wrong way? Is the system positive earth, or has it been changed over to negative earth?
(ammeter also went straight past 12 volts when the battery was connected) or does it sound like a short?
I'm sure you meant
12 amps, and not 12 volts?
Sounds as if there's a short, or the battery was connected the wrong way?
Is there a fuse in the system, as it ought to have blown?