6 volt 2CV coil questions.

[SMBIKE]

Hi all,
I'm building a citroen engine (SM) motorcycle but I'm struggling with the choice of coils because I've done away with the distributor.
I think I can use two pairs (8 outputs total) of 2CV 6volt coils, each pair wired in series, one pair per bank of three cylinders, this would mean one coil output would be redundant in each pair
The questions I have are:
1- What is the primary and secondary resistance of a 6 Volt coil
2. I notice the coil is bolted together; can I remove half the coil so I only have one output?

Thanks

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[howardjs]

Hi, Well that's some machine, regarding the coils, as the 2CV coil has a single secondary winding it means that both ends must be connected to a plug to get a spark. Many twin cylinder bike coils are like this, BMW, Harley etc.. So leaving one end open will not work. Also for the same reason it would not be possible to split the coil body (apart from loosing all the oil as well).
Is there no car coil pack you could use?
Howard

[Ken Hanna]

SM bike,
iirc, an SM engine is a 90* V6, so your best bet might be to modify something like the Boyer Bransden kit which was built for 3 cylinder motorcycles, using 3 x double-ended 12 volt coils for the sparks.

Those bikes which spring to mind are the BSA/Triumph triples...
http://www.ebay.co.uk/itm/KIT54-BSA-A75 ... lRqQLqo9kw

...or one of Boyer's offerings for Japanese two-stroke triples?
http://www.medial.se/suzuki/ignition/bo ... nsden.html

[SMBIKE]

The problem I have is that the engine is odd fire, each cylinder in the row of three fires 120 apart but the banks are 90 degrees out of phase, this means I can't use a single ignition, unless there is some clever programmable system to allow for the odd firing.

It's like running two laverda or triumph triples 90 degrees out of phase. I think I will need to use two ignition modules, one for each bank but I don't want to have 6 coils, I'd rather have 4; 1x dual and 1x single output for each bank, wired in series and driven by one module each, I'm thinking the 6volt coils in series will have a similar resistance as one 12volt coil but I could be barking up the wrong tree.

I'd like the primary resistance of a pair in series to be 3 ohms

[Ken Hanna]

Chris,
got to get your questions about this bike out of my head and stay focussed on January's main headache, which is to make sure that the perishing VAT and tax returns are done and dusted asap.

Anyhow, it's a pity that there doesn't look to be enough room on the bike for a cut-down distributor, which would allow you to use a pair of Pertronix ignitors mounted on a base plate to trigger a set of coils, with one of the pickup/trigger heads offset to cater for the engine's 'odd-fire' characteristic.
Apologies for the mention of a tractor, but this was the only Pertronix unit I could find which is designed for a 3 cylinder engine...
http://pertronix.carshopinc.com/product ... 88931/1231

Alternatively, costing many more $$$, but suitable for mounting onto the (rear) end of the camshafts, are the Pazon offerings, since they have electronic control of ignition advance.
It's not clear, but it would appear that both of these fire all of the coils simultaneously, as do the Boyer units I mentioned in a previous post.
Using the 3 x 3 volt PVL coils or the 'dual plus single' resin PVL coils would certainly be neater that a quartet of 2CV coils, with one of those in each bank having an HT post grounded, wouldn't it?

http://www.pazon.com/ignition-system/altair-triple
http://www.pazon.com/ignition-system/smart-fire-triple

p.s. I've been using this type of ignition on 2CV engines for some time now, waiting until the first one I built had covered 100,000 miles before putting some more together. On my own cars, I've fitted a pair of trigger units on the backplate, so that if one ever did fail, it's just a few minutes job to swap over to the backup unit. https://www.flickr.com/photos/30132857@ ... BHz-9C6Tjb

[SMBIKE]

Ken, thanks for all the info, I'd looked at the Pazon but they are expensive and I'd still have to chop it
I wish my electronics knowledge was better because they are selling Boyer BSA triple modules for £70 on ebay but I'm not sure I can make the pick-up coil plate to hold the two pairs of pick-ups required to drive two modules, they're may be a way to trigger it with a single pick-up.

What I have got at the moment is a 90's Ducati ignition, this came as standard with two pick-ups, one for each cylinder, each driving a module, the pick-ups ran off the crankshaft spaced at 90 degrees, I now have this setup running off the camshaft (half speed) with the coils spaced at 45 degrees, the trigger wheel has three lobes instead of just the one on the ducati. My main concern with this setup is that the extra coil may blow the modules

There is a Czech company that makes a module to replace the pair of Ducati modules and works with the pick-ups, it's also programmable where as the Ducati modules use the width of the trigger lobe to determine advance.

I got to look at the 2CV coil and they are massive, I will use 2x pairs of dual outlet motorcycle coils like you suggested.



Thanks for taking the time to provide such useful info