Running a 6v coil on a 12v system

chasbmw

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Aug 30, 2011
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I have a 6v Velo fitted with coil ignition.

I will be shortly converting the bike to run on 12v (to suit an electric starter)

The bike is currently running an almost new Trispark 6v coil.

Do I need to change to a 12v coil.

I have feeling that someone here could help

Cheers Charles
 
You have two options. Insert a ballast resistor, for example from a Commando, in series with your 6-volt coil, or the better option is to fit a 12V coil. Running the 6V coil on 12V will likely give it a short life.
 
The difference between a 6v coil and a 12v coil depends on the system. Usually it just means the wire is a larger diameter on the 6v coil. However, if the coil is paired with a magneto, (including ET Ignition or capacitor) the coil may only have a single winding in it, where a conventional coil has a primary and secondary winding in it.

6v coils usually have a higher output due to less resistance in the coil windings. Tri Spark recommends in their manuals that you run 6v coils over 12v coils.
 
maaseyracer said:
The difference between a 6v coil and a 12v coil depends on the system. Usually it just means the wire is a larger diameter on the 6v coil. However, if the coil is paired with a magneto, (including ET Ignition or capacitor) the coil may only have a single winding in it, where a conventional coil has a primary and secondary winding in it.

6v coils usually have a higher output due to less resistance in the coil windings. Tri Spark recommends in their manuals that you run 6v coils over 12v coils.
Click to expand...
NB: the Tri-Spark recommendation is for two 6V coils in series for a 12 volt system (which essentially makes a single 12V coil) not as a blanket recommendation including singles:

"Caution: use the recommended Tri-Spark coils – wrong coils will damage. For Twins use two of our IGC-1006 six volt coils, 1.8 Ohm primary resistance. For Singles use our IGC-1012 twelve volt coil, 3.6 Ohm primary."
 
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