Boyer on a Triumph, info needed

Hi,
Last week I installed a Boyer ignition on a 1970 Trophy 650. The fellow that owns the bike provided the ignition.
I did not see anything on the box or on the installation instructions that indicated that it was a Triumph specific
ignition kit. I say this because I am wondering about the hook up. Nortons use 6 volt coils but feed them through a ballast resistor.
When installing a Boyer you disgard the resistor and connect them in series thus making a dual outlet 12 volt coil (electrically speaking).
Now this Triumph used 12 volt coils stock so when I connected them in series (according to the instructions with the box) didn't I
actually create a 24 volt coil (electrically speaking) that is now only being feed by 12 volts? Am I correct or is there something I am not
seeing?

GB

How does it run?

geo46er said:

Now this Triumph used 12 volt coils stock so when I connected them in series (according to the instructions with the box) didn't I
actually create a 24 volt coil (electrically speaking) that is now only being feed by 12 volts? Am I correct or is there something I am not
seeing?

Click to expand...

Yes, two 12V coils in connected in series must share the available voltage, so each 12V coil is basically operating at 6V which does reduce the coil output voltage.

However, Boyer Bransden consider this arrangement to be "satisfactory" if the compression ratio isn't too high, but it also states that two 6V coils (or a 12V dual coil) will give best results.

http://www.boyerbransden.com/pdf/KIT000 ... 00023_.pdf

4) For low compression engines two 12 volt coils in series are satisfactory, but for racing and high compression engines two 6 volt coils in series or one 12 volt double ended coil with a primary resistance of 3 to 4.5 ohms will give the best results.

Click to expand...

I think I must be pretty dumb. I use a Boyer on my Seeley 850 with a 12volt double ended Honda coil, and it works fine, however I only use a very small 12 volt wet cell battery, and it is total loss. You mighht find that the charging circuit can affect the Boyer.

acotrel said:

I think I must be pretty dumb. I use a Boyer on my Seeley 850 with a 12volt double ended Honda coil, and it works fine, however I only use a very small 12 volt wet cell battery, and it is total loss. You mighht find that the charging circuit can affect the Boyer.

Click to expand...

Two 6V coils or one 12V dual coil is the preferred setup so why "dumb"? I don't follow you reasoning why the standard charging circuit could affect the Boyer?

When the voltage changes across an ignition coil, is when it fires. A ballast resistor probably changes the coil's sensitivity to voltage changes from the charging circuit. Also some models of Boyers have the silicon chip in them and might be susceptible to misfire, through impulse from the charging circuit.

acotrel said:

When the voltage changes across an ignition coil, is when it fires. A ballast resistor probably changes the coil's sensitivity to voltage changes from the charging circuit.

Click to expand...

Well, I've never heard of standard coils being affected by voltage changes caused by the charge circuit before.

acotrel said:

Also some models of Boyers have the silicon chip in them and might be susceptible to misfire, through impulse from the charging circuit.

Click to expand...

Under certain conditions digital ignitions can be affected by the electrical interference from charge circuit wiring especially if the alternator and ignition pickup wires are run parallel to each other, however I've not heard of any apparent problems with the standard charging circuit affecting any Boyer on a Triumph twin and there's no evidence that the Boyer concerned is a digital type.

A friend of mine who use d to be very successful racer, mentioned he had trouble with a Boyer on a Triumph. The one on my Seeley 850 never misses unless my battery goes flat, and it gives a bit of warning.

I've never had any problems with the Boyer on my T120, but it's wired with two 6 volt coils in series and the bike is a 1st or 2nd kick starter.
Maybe there's better out there but I've had nothing to compare it to.

Webby