I am just trying to sort the wiring on a newly aquired cafe racer and I just want to check whether it's 12 or 6 volt (I am presuming the later). The engine bottom half is from a 99 dominator with a magneto ignition and an alternator. There is cuurrently no battery fitted.

Is there a simple check to do to tell me for sure?

Appreciate it guys

Jamie

are there lights installed? if so, read the voltage on the bulbs - if they say 6, it's probably 6, if they say 12 it could be either. can you spin up the alternator and measure the output?

If not 12V already, it's a good and easy conversion.

Badgerman wrote:Is there a simple check to do to tell me for sure?

1. A 12V system would have zener diode (unless a modern reg/rec unit has been fitted?).

2. Check if you have three alternator wires? If so, are they green/yellow, green/black and white/green?
If wired for 12V, the green/yellow and green/black wires will be connected together somewhere between the stator and the rectifier (or reg/rec unit).

(However, if you happen to find a modern reg/rec unit with three (yellow?) wires connected to three sepatate stator wires then someone could have fitted a 12V three-phase high output system.