Buying a Tri-Spark - question about coils

I'm buying Tri-Spark to replace the Joe Hunt magneto that was fitted by the previous owner of my '74 Commando 850.
Being new to bikes and mechanics, I'm uncertain about the pros/cons of the various ignition coil voltages, so am uncertain which to choose, and why.
My understanding is that the "standard" voltage is 12volts, but you can also buy 6 and 4 volt coils. I've been told that a lower voltage = hotter spark, and (therefore, or coincidentally?) lower draw on the system.
I neither know if that is true, nor whether that would actually be an advantage.

Does anybody have the inclination to provide a bit of info, to help a newbie make a selection? Any info would be greatly appreciated.
Thanks!

I assume you are buying the Tri-spark from CNW? Follow their advice. I am guessing they will advise you to buy one of their coils, it isn't just sales hype. It will help out if you have warranty issues with the ignition.

Russ

Actually, I was looking directly at the http://www.trispark.com.au site.
I'll check out CNW - I'd much rather purchase something from North America.

gardenzombie said:

My understanding is that the "standard" voltage is 12volts,

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Yes, but the standard coils for the original points ignition are 6V (17M6) as each coil is wired in parallel to the other, for points operation, but they are also wired in series with a ballast resistor (check the '71-on wiring diagrams in your manual).

The majority of electronic ignition systems for Commandos work on the "wasted spark" principle where the ballast resistor is removed and the two 6V coils are then wired in series so both coils/plugs spark simultaneously.

If you intend to fit the Tri-Spark Classic Twin system then it will require either two standard type 6V coils or a 12V dual coil of the correct primary resistance.

http://www.trispark.com.au/images/Class ... 202013.pdf

Coil circuit resistance range: 3.0 to 5.0 Ohms (3.0 absolute minimum)

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If you are going with a highend unit like the Trispark or Powerarc then it is advisable to match it with a good coil system. You can find Dyna Coil by google (5.0 ohm).

If you want to maintain originality then Trispark has what you need in that regard. If that is not important then the Powerarc coil from Oldbritts is very good.



The coil from Old Britts that is suggested for the Powerarc will do just great I am sure, for the Trispark.
http://www.oldbritts.com/51_150102.html

rvich said:

I assume you are buying the Tri-spark from CNW? Follow their advice. I am guessing they will advise you to buy one of their coils, it isn't just sales hype. It will help out if you have warranty issues with the ignition.

Russ

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+1. Get it from CNW, they're the best.

Snorton74 - this is unrelated, but I have the t-shirt that goes with your avatar. I got it from threadless, not sure if it's still available or not. I've since found out the image on it is lifted from a French zombie movie called "The Horde".