Author Topic: convert to 12v.  (Read 897 times)

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convert to 12v.
« on: November 30, 2008, 11:17:22 am »
From: anthonyofcamberley  (Original Message) Sent: 30/12/2007 15:32
I am restoring a C11G and have to purchase battery,bulbs,coil.What are the merrits in converting to 12V,other than brighter lights.Will I get a better spark at the plug and what is involved.i,e will the alternator cope.
Thanks in anticipation.

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From: BSAC12ver Sent: 30/12/2007 17:52
Hi AnthonyofCamberley

Well this is only my opinion so see what the other chaps have to say as well.

I did stick to 6 volts and brought a 6v halogen headlamp bulb.

Get rid of the "cheesecutter" rectifier and get a modern one.

I have only had to replace 1 bulb in 17 years, my charge rate on the ammeter is always healthy and I ride with the lights on. day or night.

I have retained positive earth.

The alternator dishes out plenty of current and I did measure something like 14v AC from it so presume ok for 12v conversion?

Be interesting to see what the other chaps think



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From: sergentwoodie1 Sent: 30/12/2007 21:30
Chaps? only the Brylcream boys were chaps,I  was an OY You, I can only say I changed to 12 volts in 1985 because my advance & retard mechanism was worn out . Spares the for C models were virtually non existant then. People could'nt be bothered hunting in the rear of stock rooms for grey porridge stuff. Consequently I went the full Boyer road  purchasing a B40 model I converted it to fit my C12. Boyer will only work on FULL 12 Volts, so I fitted the Boyer conversion as well as their electromic ignition kit. Marvellous lighting half the amperage in the wireing system,  converting to 12 volts will  not necessaraly give one a better spark.The Boyer unit I have not touched inclueding timing in, wait a mo 1985 -2007 oh 22 years.I also have a dry cell 12 volt battery inside the  Black case.

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From: BSAC12ver Sent: 31/12/2007 12:49
Got to admit Woodie that "chaps" do sound a bit grand!
If your ignition system is doing away with the advance retard " wind up gramophone centrifugal governor" then that must be a good bet!

I am I suppose a "tight $od" (you can call me this if you wish ole friend!) and have made do with what I had I suppose

If the cost is not a problem then AnthonyofCamberley it would seem a good idea to me.

Ere Sarge if you was the Sarge how come you got the "oy you!!!" ???

Only having a bit of fun Woodie youur a smashing ch........ oops I mean geezer!!!!
Take care


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From: sergentwoodie1 Sent: 31/12/2007 17:48
Whatcha Richard Lad. I certainatly was'nt rollin in dosh but it was the only way at the time , We had no Autojumbles or Internet or ebay just hours on the phone when was off duty  contacting Dealers who were not interested. I was'nt born with 3 tapes on my pyjamas  I started as a Nuffink happy New Year to You & Yours. Just Woodie
 AEC 10 tonner.jpg   

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From: bsa_C11G Sent: 01/01/2008 12:28
If your biggest problem was the weight of the money in your pockets slowing you down then would not be on this list, thats for sure.
Now as for your dilemma.
It all depends upon what you want to do with the bike when it is finished.
The cheapest initial route would be to get a modern full wave inverting rectifier from an oriential motorcycle wrecker .
Terminate the wires from your original selinium 1/2 way non-inverting rectifier some where inside the loom so that the bike retains its period look & find somewhere to secret the modern replacement.
The only down side to this is that 6V anything now days is becoming hard to find & subsequently much more expensive than its common 12V cousins.

The 12 V route is basically the same except that you fit a 12V rectifier instead of a 6V one & then replace all globes, coil & battery.
You can retain the original 6 V coil if you put a shunt resistor across it like on the cars that run a 9V coil ( to get better spark during start up). If you keep the original 6 V coil in a 12 V system it is prudent to fit the et points cam ( round with a flat cut across it) which will limit the time that the coil is in circuit soaking up twice the volts that it was designed to cope with.
You can also keep the original 6V horn ( although you will need to adjust it) provided that you only use it in short blasts 10 sec or less and spareingly at that.

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From: 1949enfield Sent: 02/01/2008 19:11
I have converted all my bikes to 12v since the late sixties when 6v bulbs became harder to get. All you need to change are the bulbs , ignition coil , and battery. I would also change the rectifier, the new ones are cheap and work better. Advantages are much better lights I use a 50w bulb, cheaper coils ,mine is from a viva which was dumped in a layby when my original failed . You can still use the same method of switches to control the charging rate or change to a zenner which charges better when the lights are not on. Graham

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From: fredbare7 Sent: 03/01/2008 15:06
Well done Graham, that's it in a nut shell. I once did the same to an old
Matchless, easy. I had hoped for a fatter spark to aid starting, but no
 improvement. Better lights thought (I also added Indicators)