coil impedance

One other related potential problem is some sort of internal break down in the stock OEM spark plug caps. I've used an ohmeter on various OEM caps and gotten widely different readings. Tore one apart and see a small hunk of what appears to be graphite so presume this was a resistence type cap for whatever reason. Was happy to see new plug caps already affixed to the Dyna plug wires -- which solved any problems due to deteriorated OEM caps. Didn't think to do an olm check on the Dyna copper core plug wires before installation, but would guess an infinity reading of no resistance.

steell wrote:

The Dyna S and the Kawasaki KZ (till at least 83) are electronic ignitions, but they don't have electronic advance.

Thanks, Steell -- you are correct of course, and the following link does indeed specifically refer to the Dyna S as an Electronic Ignition .

www.z1enterprises.com/detail.aspx?ID=200


Believe I was confusing kinship between an Electronic Ignition and a CDI (Capacitor Discharge Ignition) which I have no experience with.


And here is the spark plug wire splicer for anyone interested:

wwwz1enterprises.com/detail.aspx?ID=1890 .


Also seem to remember from the archives (or possibly somewhere else) an article describing how to remove the old molded in plug wires from the OEM coils and install new plug wires into the OEM coils.

Most coils associated with Kaw points ignitions and non-cdi type ignitions are called 3 Ohm coils. Aftermarket varieties of these coils sold currently are Dyna and Accel coils. The Dyna coils measure nominally 3.7 Ohms and the Accel coils measure 4.2 Ohms primary impedence.

If you are interested in using 2.5 Ohm coils, this is a bit too low and the coils will run hot I think. In any case, Kaw used 2.5 Ohms coils on some electronic ignition models but also used a 1.5 Ohm inline ballast resistor. Unfortunately, MOST of the older sets of these coils and associated ballast resistors have crept up in resistance over time and when you measure impedence you find it much higher than originally spec'd so the coils will give a poor spark.

Found this link with more detail regarding electronic ignitions, coils, plugs and plug wires --

www.breakerless.com/igntionfacts.htm#Electronic%20Ignition

loudhvx wrote:

The lower the resistance of the coils, the more heat is dissipated at the points. The more heat that is dissipated, the more metal is transferred from point to point. Bottom line is that the points wear out much faster with lower resistance coils. I know one ohm does not seem like a lot, but the current increases by 60 %. Power dissipation increases by the square of the current so the heat increase is considerable when going from 4 ohm coils to 2.5 ohm coils.

Impedance is not really an issue. Resistance is the issue. Since the coil-current reaches a DC state rapidly at idle, it becomes a simple DC-resistance problem. Therefore, as Steell said, you can simply just add some resistance. About .5 to 1 ohm should be fine. It's not very energy efficient, but should work, and is cheap, which is what I presume is the goal. <br><br>Post edited by: loudhvx, at: 2006/11/26 02:05

well spoken and good job!

wiredgeorge wrote:

Most coils associated with Kaw points ignitions and non-cdi type ignitions are called 3 Ohm coils. Aftermarket varieties of these coils sold currently are Dyna and Accel coils. The Dyna coils measure nominally 3.7 Ohms and the Accel coils measure 4.2 Ohms primary impedence.

If you are interested in using 2.5 Ohm coils, this is a bit too low and the coils will run hot I think. In any case, Kaw used 2.5 Ohms coils on some electronic ignition models but also used a 1.5 Ohm inline ballast resistor. Unfortunately, MOST of the older sets of these coils and associated ballast resistors have crept up in resistance over time and when you measure impedence you find it much higher than originally spec'd so the coils will give a poor spark.

a weak spark is my primary problem..can i get these resistors anywhere? the ones for use with lower ohm coils? if my points are meant to be used with 3 ohm coils, the ones i have now are 2.5-2.7 range...its amazing that i little difference like that would be a problem.

Post edited by: arobsum, at: 2006/11/26 19:43

The problem with using coils that are too low in resistance isn't that the coils will overheat, but that the points or ignitor will run hot. The only time the coil will have a problem is if the dwell is way longer than intended.

Most full-size coils in the 2.5 to 4 ohm range are able to withstand very long dwell times. Mini-coils need dwell-control systems. (Luckily, the Kaw pickups are able to provide dwell-control if they are used properly.)

All of the Accel 3-ohm coils I've had measured exactly 3 ohms. The dozen or so Kaw electronic-ignition-coils I've tested had plenty of spark and were all in the 2.4 to 2.7 ohm range, even after 25 years. But old coils will eventually fail, usually in rain storms just when you need them to NOT fail.

Resistor wires or resistor plugs or resistor caps are needed to keep rf noise down. some electronic ignitions are susceptible to rf noise.

Post edited by: loudhvx, at: 2006/11/27 02:19

I doubt the Kawasaki ballast resistor is still available but you could try bikebandit.com or some other OEM parts source. I have been told that it is possible to buy automotive inline ballast resistors at autoparts stores but I asked at a couple and they don't appear to be a stock item anymore. Apparantly at one time, they were fairly common for some reason but are not used in more modern applications.

i'll check into the automotive resistors.. thanks everyone for the input.

one last question...will these 2.5 ohm coils work as is with an aftermarket ignition?(DYNA)

Yes, but the same issue exists. The Dyna recommends using 3.0-ohm coils or higher, so you'll still have to add resistance. 1-ohm resistor will work in that case too. If you use a standard 1-ohm resistor, it needs to be about 50 watts.

If I recall, OnkelB used 2.5 ohm coils with his dyna ignition and didn't have a problem. Dyna just recommends the 3-ohm coils, but maybe their ignition can handle the extra current from the 2.5-ohm coils.

ok..thanks. i guess either way i need to get a resistor. thanks for all the help everyone. i'll let you all know how it turns out.