Resistor caps and spark plugs

The bike has a Dynatek 2000 ignition and 3ohm mini-coils.
I have been running solid core wires with non-resistor caps, and BR8EIX (resistor) iridium spark plugs.
Just got a new set of Dynatek (solid core) wires DW200 which came with the wrong crimp-on ends to attach at the coils. A call to Dynatek left me confused...again.
Dynatek highly-suggested to cut wires to length, and put the resistor caps back on the cut ends, and attach them to the spark plugs. That is how Dynatek recommends it be done, other than using resistor wire sets. :huh:

WTF?
I was under the impression all that was needed was one (1) resistor in the setup per plug, and that having a R resistor spark plug accomplishes that necessity.
So, what difference does it make? HELP. :blink:

My understanding, is the resistor is used to suppress the electrical noise when the plugs fire. I'd think adding resistance, along with using resistor plugs would reduce the spark energy.

Agreed. So why the resistance from Dynatek to run the 2000/mini-coil setup with no resistors, except in the spark plugs?

I sensed (Dynatek) concern for the well-being of the 2000 ignition module, perhaps potential damage(?) cause by electrical noise or interference?

daveo wrote: Agreed. So why the resistance from Dynatek to run the 2000/mini-coil setup with no resistors, except in the spark plugs?

I sensed (Dynatek) concern for the well-being of the 2000 ignition module, perhaps potential damage(?) cause by electrical noise or interference?

Good question, I would ask them directly. I ran non-resistor wires/caps and plugs for many years, no problem with the standard points ignition.

In general, you only need to add the resistance once (either wires, cap or plugs) not twice. It is possible that Dynas are overly sensitive to the EMI and they want "double protection". I would ask them straight out if that's why.

Interesting question as to how much difference it would make in spark energy. The "coil" is actually a flyback transformer system. During the non fire interval, current flows in the primary which is stored in the transformer core as energy of 1/2 L (I) squared. When the points open or the solid state switch opens, it dumps the stored energy out of the secondary winding through the spark plugs. The radiated EMI occurs because the transformer inductance and winding capacitance along with wire resistance form an R-L-C tank circuit that oscillates at high frequency for a brief time. Adding more series resistance lowers the oscillation frequency and also damps out the ringing.

Even though doubling the resistance by adding both resistor wire and plugs seems like it would cut spark energy in half, I suspect the loss is very much smaller. The wires and spark plug are in a series circuit with an air gap which is many millions of Ohms of resistance so the added resistance in front is small compared to the gap resistance. I don't know if running double resistance would make any noticeable difference. I doubt it if Dyna is recommending it.

bountyhunter wrote: Even though doubling the resistance by adding both resistor wire and plugs seems like it would cut spark energy in half, I suspect the loss is very much smaller. The wires and spark plug are in a series circuit with an air gap which is many millions of Ohms of resistance so the added resistance in front is small compared to the gap resistance.

I think your explanation is right on. I believe that additional series resistors should cause a minimal loss. At the same time I also agree that only one resistor should be necessary, and the "R" plugs should do the trick.

The issue here is with the Dyna 2000 control unit (points don't care one bit). Since this gizmo is microprocessor based, it's susceptible to interference from spark noise (EMI). EMI could cause several types of faults. The worst would be it may crash or lock up or reset, but more likely the noise could be misinterpreted as a valid trigger input from the crank sensor and cause the plugs to fire at the wrong time, too often, or totally at random.

My guess is that the bad things that could happen if EMI were to confuse the Dyna 2000 are likely to be much worse than the small amount of spark energy you lose by running too many resistor elements.

I would not be surprised if Dyna recommended multiple resistors, since they can't control where the 2000 box is installed on the bike or how it's wired. Some locations and setups could be a lot worse than others. Maybe they've found that people generally have better luck if they add as much EMI suppression as possible.

dohc wrote:

bountyhunter wrote: Even though doubling the resistance by adding both resistor wire and plugs seems like it would cut spark energy in half, I suspect the loss is very much smaller. The wires and spark plug are in a series circuit with an air gap which is many millions of Ohms of resistance so the added resistance in front is small compared to the gap resistance.

I think your explanation is right on. I believe that additional series resistors should cause a minimal loss. At the same time I also agree that only one resistor should be necessary, and the "R" plugs should do the trick.

The issue here is with the Dyna 2000 control unit (points don't care one bit). Since this gizmo is microprocessor based, it's susceptible to interference from spark noise (EMI). EMI could cause several types of faults. The worst would be it may crash or lock up or reset, but more likely the noise could be misinterpreted as a valid trigger input from the crank sensor and cause the plugs to fire at the wrong time, too often, or totally at random..

That's true, that's why I would ask Dyna straight out if they are recommending two resistors to address a specific problem they know about. It sounds like they are and if so, then it is safest to follow their advice.

Well, here's the setup now. It runs...:whistle:

What plugs did you end up with?

koolaid_kid wrote: What plugs did you end up with?

I'm back with the good-old NGK B8ES, for now anyway. The platinum plugs work nice, but will see how they compare. A little more to do, then back under the cover for awhile.
It will be quite some time until roads are salt-free around here again, and I'm trying to (not) go nuts waiting..:pinch:

Thanks.
I worked at Cummins Engine and we ran some tests on spark plugs. We concluded there was no difference in the performance of any style of plug, but the iridium plugs did have longer life than the standard plug.

koolaid_kid wrote: Thanks.
I worked at Cummins Engine and we ran some tests on spark plugs. We concluded there was no difference in the performance of any style of plug, but the iridium plugs did have longer life than the standard plug.

Just curious, why would a diesel engine manufacturer test spark plugs?

koolaid_kid wrote: Thanks.
I worked at Cummins Engine and we ran some tests on spark plugs. We concluded there was no difference in the performance of any style of plug, but the iridium plugs did have longer life than the standard plug.