ignition coil compatability

cool, what were you thinking?

bountyhunter wrote:

Just out of curiousity:

If it had 2 Ohm coils stock, does it have external ballast resistors?

I was wondering if you could just remove the ballast resistors and use the standard 4 Ohm coils that most of the old kawis use (they cost less).

Most did not have a ballast.
Because the dwell is shorter on the electronic ignition than the points ignition, you would lose spark energy on the 4-ohm coils at higher RPMs (compared to using the 4-ohm coil on the points ignition). So, even though the 4-ohm coils might work fine at lower RPMs (where dwell TIME is in abundance), it may not work well at high RPMs.

The dwell at 10,000 RPM is only 2 msec with the electronic ignition. With the points ignition dwell is 3 msec, that's 50% longer. The electronic ignition needs a coil that charges faster.

I thought the Kawasaki electronic ignitions (1979 and 1980?) that used ballasts had 1.5-ohm coils. After that, the coils appear to be in the 2.5-ohm range with no ballasts. Then much later, they went to 3.0-ohm, from what Otakar said.

Interesting they used such low impedance coils. On the typical CD (capacitive discharge) electronic ignitions, the low impedance coils will blow them out because the peak current is too high for the polycarbonate capacitor to handle. I suspect the kawi electronic ignition is not CD.

bountyhunter wrote:

Interesting they used such low impedance coils. On the typical CD (capacitive discharge) electronic ignitions, the low impedance coils will blow them out because the peak current is too high for the polycarbonate capacitor to handle. I suspect the kawi electronic ignition is not CD.

Correct, it's transistorized Kettering, (aka flyback).

But most CDI's I've seen use coils in the .5 to 1.5 ohm range, presumably relying on the inductive reactance to keep the current low, initially. That way, by the time the current starts to get high, the cap's voltage drops enough to avoid over-current. This would mean the capacitor would have to have a well-matched coil to get the most out of it without blowing up the cap.

hi there the cheap easy fix is some coils of a mid 80s gpz there are electronic ignition coils but are ok on points ignitions the benifit of these is you can fit nice HT leads you will have to make a small mounting bracket ,no big deal i do not have my set hear they are on a mates bike so can not give you the part number, will get back on that as soon as i can .i did 40000 miles on them no problem , have got dyna on now so even better. zigzag

I too, have wondered about the need for resistor plugs, the Dyna wires come with plugs that look ok. Anybody know on that one?

loudhvx wrote:

bountyhunter wrote:

Interesting they used such low impedance coils. On the typical CD (capacitive discharge) electronic ignitions, the low impedance coils will blow them out because the peak current is too high for the polycarbonate capacitor to handle. I suspect the kawi electronic ignition is not CD.

Correct, it's transistorized Kettering, (aka flyback).

But most CDI's I've seen use coils in the .5 to 1.5 ohm range, presumably relying on the inductive reactance to keep the current low, initially. That way, by the time the current starts to get high, the cap's voltage drops enough to avoid over-current. This would mean the capacitor would have to have a well-matched coil to get the most out of it without blowing up the cap.

THe CD's I have worked on were designed to work with coils in the 4 Ohm range. The so called "high performance" coils (which were lower in resistance) blew the CD's capacitor.

On mine, the CD cap is charged up to about 400V during normal operation and that voltage is instantaneously forced across the coil's primary when the SCR fires. Both the resistance and inductance limit the peak current, but I think the "high perf" coils are lower on both. At any rate, they seem to blow out aftermarket CDI modules.

Pro_window78 wrote:

I too, have wondered about the need for resistor plugs, the Dyna wires come with plugs that look ok. Anybody know on that one?

Resitor plugs and wires are not mandatory, but they do reduce the amount of radio interference that gets shot out when the plug fires.

So on a 78 kz1000 with no electronics, it should'nt be a prob. coool

Pro_window78 wrote:

So on a 78 kz1000 with no electronics, it should'nt be a prob. coool

The only prob you may have would be with digital multimeters or electronic tachs etc.

If you have resistor plug caps, though, then you already have suppression. Also, are the dyna wires solid core? If not they may be suppression too.

$50 is about half price. I would be happy with that if it will help you out.

sounds like a deal ill pm you for details instead of using this thread.