Two wires on my stator

[VintageBike]

Guys,
am just finishing my first restoration (picture attached).  Everything is fine except for the charging system.  The stator that came with the bike has just two leads (green/yellow and green/white).  The wiring diagram and harness are both expecting three leads from the stator (green/yellow to coil, green/white to rectifier and green/black also to rectifier).  Can anyone advise on whether this alternator can be made to work in this environment?

Cheers

Nigel

[L.A.B.]

Everything is fine except for the charging system.  The stator that came with the bike has just two leads (green/yellow and green/white).  The wiring diagram and harness are both expecting three leads from the stator (green/yellow to coil, green/white to rectifier and green/black also to rectifier).  Can anyone advise on whether this alternator can be made to work in this environment?

Nigel,

Yes...  

IF the electrical system has already been converted to 12V?



If so, then the two wire alternator should work OK connected to the rectifier, provided a Zener diode has also been added to the system?

If not, then the conversion isn't difficult to do.

Check for a stamped Lucas part number and date stamp on the periphery of metal stator frame ring, as that number should identify the stator type, which I'm guessing is probably a Lucas RM21?

The third stator output wire (GY) in the 6V three wire system that originally connected to the ignition switch (not ignition "coil" as it is  labelled in the diagram) was the for the headlight, or alternatively it could be switched on for "Emergency Starting" (Does the Ign, Sw have an "EMG" position?)

6V System:  http://www.bsa-c15.org.uk/ > 6V Wiring
12V conversion: http://www.bsa-c15.org.uk/ >Convert to 12V

(note in the 12V diagram how the original 6V three-wire alternator is converted to 12V by connecting the GB & GY wires together.)


(The bike looks good anyway!)

[VintageBike]

Thanks Les.

If I understand you correctly, this stator is only good for 12v operations? The bike has not been upgraded to 12V (I know I should have...!) , but yet this stator is certainly the one that the bike has run with for donkey's.

Yes the IGN switch does have an EMG position.  I can certainly live without this (as I still have enough energy in my legs to bump start).

Nigel

[L.A.B.]

If I understand you correctly, this stator is only good for 12v operations? The bike has not been upgraded to 12V (I know I should have...!) , but yet this stator is certainly the one that the bike has run with for donkey's.

So, can you find any stamped numbers on the stator?

[VintageBike]

sorry Les, I will check this out tomorrow.  Family is calling.....

Nigel

[VintageBike]

In time honoured fashion, there is nothing on the stator to indicate the model number....  All I do know is that it worked fine from 1973 to 1983 when the bike was retired!

Nigel

[L.A.B.]

In time honoured fashion, there is nothing on the stator to indicate the model number....  All I do know is that it worked fine from 1973 to 1983 when the bike was retired!

Oh well...in that case, I'm at a loss to know what you've got? As it ought to be an open coil RM13 unit I would have thought?

As the only 'two-wire' stators that I know of, are 12V ones!

If it was working before the lay-up, then I suppose it should still be OK now?

I suggest that you check the output voltage once you've got it going, obviously it should have a 'third' output wire connection to the Ign.Sw?
So if the lights work, then something's not wired as it would have been originally, according to the C15 wiring diagram?

Was there ever a 12V version C15?