Sparx alternator and electronic ignition

MikeG · Aug 13, 2012

I have a Sparx 3 phase alternator on my 71 Cdo, which required the fitting of 5000 ohm resistor caps on the existing copper core plug wires. I'm now considering putting an Old Britts electronic ignition on, which requires carbon core resistor wires, and resistor plugs. I'm thinking that if I go that route the resistor ends on the plugs would be unnecessary and probably detrimental as well. Any body out there have any thoughts, comments or experience as far as this goes?
Thanks
MikeG

Whitworth Ranch · Aug 13, 2012

You should only need one form of resistance. Resistor cap or plug or wire, no "ands". In automotive I replace carbon "wires" when they show more than 20k ohms. If the ignition maker calls for more than one type of resistance, I would be interested to know the reasoning.

Edit: Power Arc is quite insistent about resistor plugs AND wires. For sure I'd ditch the caps... Any mega electrical guys out there?

dougmatson · Aug 13, 2012

On my 850 I run a sparx 3 phase and the PowerArc from OldBrits with no problems just use the resistor plugs they recommend.

maylar · Aug 14, 2012

Resisor caps are typically 5000 ohms and wires typically 4-5000 ohms per foot. With such a short wire length on our bikes I'd probably use the caps alone.

FWIW I have Sparx 3 phase and run solid wires with standard plugs and never had any issues. TriSpark ignition.

Rob_in_scotland · Aug 17, 2012

As I discussed in one of the previous threads, I fitted a Sparx 3 phase alternator and voltage regulator along with the 5000 ohm plug caps as recommended. After 800 miles I checked the voltage output and found that over 2500 rpm it was overcharging. I confirmed this with a voltmeter. As another contributor noted, the high voltage could affect the electronic ignition. I returned it to the supplier (Tri-Cor England) who just told me that it was outside the warranty and the maker would just laugh he if he tried to return it. I have ended up buying another brand of regulator from another supplier which functions correctly. My advice would be to check the voltage once you have fitted it, not just see that the orange light goes out as I did.

MikeG · Aug 17, 2012

Rob_in_scotland said:
As I discussed in one of the previous threads, I fitted a Sparx 3 phase alternator and voltage regulator along with the 5000 ohm plug caps as recommended. After 800 miles I checked the voltage output and found that over 2500 rpm it was overcharging. I confirmed this with a voltmeter. As another contributor noted, the high voltage could affect the electronic ignition. I returned it to the supplier (Tri-Cor England) who just told me that it was outside the warranty and the maker would just laugh he if he tried to return it. I have ended up buying another brand of regulator from another supplier which functions correctly. My advice would be to check the voltage once you have fitted it, not just see that the orange light goes out as I did.

14.3 volts at 3000RPM.

Sparx alternator and electronic ignition

MikeG

Whitworth Ranch

dougmatson

maylar

Rob_in_scotland

MikeG

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