Wragnition coil ignition from a magneto

[michael.leach]

I had my magneto converted about 8 years ago to provide the low tension to a remote coil under the tank. This work was done by Tony Wragg who advertised at the time in CHEVAL de FER I believe Tony is now retired and so am I and the bike is about ready to go. I have recently cooked a coil on another bike and this has got me thinking if I ever had trouble with the coil on Tony's system where and what coil could be used as a replacement I entered the details off the coil on the net and drew a blank. Can anyone enlighten me as to the specification requirements of the coil and tell me a bit more about this practice of using a magneto to provide the power to an HT coil. I believe this has been done quite successfully by a few people even going it alone in their own garages and sheds.

[Steven.Carter]

Well the power for the coil comes from the battery not the mag. The magneto is used just for timing the spark. So I suspect any 6volt or 12volt coil will do,whichever your bike is running on.
Steve

[keith.hodgenia]

I am not familiar with this conversion. However. I did the same sort of thing with a Villiers ignition system. (low tension coil feeding an external HT coil ) The first coil I tried was designed for a CDI system and didn't work. The next one I tried came from a guy call Norman norman@njbshocks.co.uk and that worked fine. he knows them as a Villiers trials bike mod. Hope this helps. Keith.

[john.mitchell]

Hi Michael. I must admit to having taken down your phone no incorrectly when you phoned so I couldn't ring back. . However I have found the reference you were looking for. The guy's name was Peter not Tony, and he was mentioned in aletter from Huw Parsons.
Letters Cheval April 04

"Wraggnition (a solution to Lucas magneto overheating?)
David Jones, the Square Four expert, came to the rescue; he suggested contacting Peter Wragg, a man David has used in the past for ‘problem’ magnetos. Peter’s modification is so simple I couldn’t believe it would work, but then again I’m no electrical wizard. He removes the high tension circuit and it’s shellac from the magneto altogether. The low tension circuit exits the magneto via the slip ring and what was the high tension terminal. From here it goes to an impulse coil earthed to a convenient point. The high tension lead from the coil then goes to the spark plug(s). No black boxes, no battery required. The coil is about 3” by 2” and on my bike is hidden in the toolbox under the saddle.
The Bike starts even more easily and seems to be running more smoothly at low revs, although I’m still running – in and so far have only done 650 miles on it. Peter has modified a lot of magnetos this way, mostly for singles and twins and including such exotica as Manx Nortons.
The only disadvantage that I can see to this system is that the brush and slip ring need to be in good condition as they are only passing low voltage - perhaps a problem on singles with their tendency to blow oil into the magneto.
The big advantage is that there is no high tension circuit generating so much internal heat and also no shellac for this heat to melt.
The rebuild cost me £150, which I believe is the going rate . This included new screws, bearings, contact breaker ETC and very high spec capacitor. The turn around was as fore warned; it was six weeks until it was my turn. I plan on doing quite a few miles on the Cammy this year, we will see if the magneto conversion is as good as I think it is!
Peter Wragg is on 01142 830382"

[michael.leach]

Thanks John
I now know I am not barmy and there was a Mr Wragg not Tony as I thought but Peter and David Jones did have one of these conversions on his bike. I would still like to find someone who has one and can tell me the specification requirements for a replacement coil. I have seen one on the internet which looks like mine and is described as a sakura AS 803, mine is a sakura but the numbers on my coil are not the same and there is no indication of the voltage on either of them.
Thanks again for your help.
Michael Leach