Author Topic: Lucas dynamos/alternators  (Read 1784 times)

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Offline AdminPete

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Lucas dynamos/alternators
« on: November 24, 2008, 02:37:57 pm »
  (Original Message) Sent: 06/04/2006 19:45
I want to replace the 6 volt Lucas dynamo with a 12v alternator. Does anyone know where I can get an alternator to fit into a BSA C11G.
In case I wasn't clear - I'm often not!

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From: PeteRudge1 Sent: 06/04/2006 20:29
Hi Galwaysal1,
The C11G engine had an alternator, not a dynamo. Are you sure yous is a C11G? If it is, I think you can run a 6v alternator as 12v by joining two of the wires together and fitting a zenor diode. But if anyone knows that this can't be done, please feel free to correct me. I have numerous diagrams and features on this subject which might take me a while to sort out, but I'm sure it can be done.

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From: Galwaysal1 Sent: 06/04/2006 21:17
Hi Pete,
thanks for your quick reply. I'm rewiring the bike from the beginning again and the original dynamo/alternator is shot. I don't know if the bike is a C11 or C11G - I thought I might be able to buy a 12v alternator and do away with the voltage control etc but need advice as to whether this is feasible. I'm trying to source an alternator that will fit in, in place of the original.
Keeping it original is not a priority as is not all original at present - it's a starter project at restoration.
I'd be grateful for any advice.
Many Thanks

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From: jinjahbiscuit Sent: 07/04/2006 09:42
Most of the later Lucas alternaters will work, both 6v and 12 v (I ran a Triumph Tiger 90 at 12v with 6v alternater and zener diode ok). You should check the bore of the rotor against the diameter of the shaft it fits on, I'm not certain they're all the same.
If you decide to go the 12v route, get hold of a Boyer voltage control box and dump the the battery too.   

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From: coltrider4 Sent: 08/04/2006 21:53
In Australia there is not much in the C12 or Colt Alternators around. I am in the process of fitting an earlier triumph alternator to an Ariel colt. It is a two wire unit that gives about 13 volts at 3000 rpm on a test bench. I imagine the colt will alway be running at around those revs just to keep up with side street traffic.
Does anyone know if the new units from USA and UK advertised in Classic Bike work on the C10L BSA and Ariel colt? Its a lot of money to spend if it does not work out.

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From: jinjahbiscuit Sent: 11/04/2006 13:54
These two web sites might be useful:
A. O. Services, 35 Griston Rd. Watton, Thetford. IP25 6DN.
Phone: +44(0)1953 884681
P. R. Goff. 62 Clare Rd. Prestwood, Bucks. HP16 0NU.
Phone: +44(0)1494 8694 868218
Both do alternaters for British bikes, and heaps of other electronics too. I'm pretty certain that the relatively more modern RM19 and 21 alternaters (both plastic encapsulated) will fit the older machines, they were fitted to just about every bike built in the UK during the late 60s' early 70s', so there's loads of them out there. I think the later 3 phase alternators may be physically bigger, but I'll stand corrected if I'm wrong.
As I said, I ran a T90 on 12v using its' original 6v alternator, by connecting two of three wires together, can't remember now which ones' but it's a common mod, so should'nt be hard to find out. Also had to fit a zener and 12v bulbs and horn.
I have a later, 1970 T100S (already 12v), which has a Boyer power box, and eloctronic ignition unit meaning no battery, rectifier or zener. Result - reliability.
Good luck with your machines.

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From: wilkybob Sent: 13/04/2006 19:23
Try this site,
Ok not 12v, but I've heard good reports on the stuff they do.