coil + ballast resistor

loudhvx - Not sure how the power would get from coils to the igniter. Please explain. This crude drawing is pretty much a replica of the OEM wiring diagram.

Your drawing shows wires from the coils to the ignitor. That's how the current gets to the ignitor. All of the current that goes through the resistor goes through the primary windings, then goes to the ignitor which completes the circuit to ground.

In other words, every electron that flows through the primary winding (and resistor) also flows through the output transistor of the ignitor (which is connected to ground). Every electron that goes through the transistor heats up the transistor a tiny bit. Too many electrons too soon will overheat the transistor.

It's just like points. You agree that the primary current flows through the points, right? The ignitor is just a substitute for points.

Incidently, your terminology is little off too. You refer to the black and green wires as carrying a "signal" for the coils to fire. Well, yes that's true, but they are not just signals. They carry the full current and power for the circuit. They are completing a power circuit.

A "signal" implies data without the power to complete the circuit. For example, an electronic tach get's a "signal" from the ignition. The signal does not power the tach, but does control it.

The black and green wires control the coils, but they also are part of the power circuit to the coils.

i had though until now that the primary and secondary windings were both powered by 12v from seperate sources and when 'signaled' the primary was discharged resulting in the secondery dicharging across the plug gap to earth - however my understanding and terminology are a little crude. well next im gonna mesure my ballast and primary resistances, and post them. i would be very interested in a circiut diagram of a home built ignitor, ta mat

sorry my description of ignition coil workings was wrong, however i see now how the current passing through the primary windings then passes through the ignitor/points to earth, so if FOR EXAMPLE my standard setup was when new: coils 2.5 ohms and ballast resistor 1.5 ohms- couldnt i replace my coils for 4 ohm ones thereby still hitting the ignitor with the same current
im still a little confused ? more questions....aaaahhh !
can you explain the layout of the secondary winding for me, i assume it has more turns than the primary to act as a stepup transformer -increasing voltage and decreasing current and that one end is connected to the ht lead- how is the other end wired ? is is a totally seperate circuit from the primary?.. cheers again

Battymatty, you have it down pretty well. You are correct about your 4-ohm-coil example.

And you are correct about the secondary... more voltage, less current, like a step up transformer. The secondary winding is connected to both plug wires. The secondary has no connection inside the coil to anything but the plug wires. One end of the secondary is one plug wire, the other is the other plug wire.

here's one of several versions
www.geocities.com/loudgpz/GPZgmHEImod.html

Post edited by: loudhvx, at: 2006/04/26 10:26

just wondering if my 78 ltd1000 has this ballst resistor or not....running dyna s ign. and accel super coils...any info appreciated..

Thanks for the explanation loudhvx!

As far as the 78 LTD having a ballast resistor, go out and look. It will be in one of a couple places. It is a white insulator block looking thing about 4 inches long... it has brass colored mounts mounting flanges on its ends. It has just a couple red wires connected... hard to miss!!! It should be mounted up in front across the frame hear where a horn should be mounted OR it will be mounted on the side of the battery box. Again, white ceramic type material about 4 inch long x 1 inch rectangle.

hi, have measured my resistances, coil primary windings are both 2.7 ohms; ballast is 1.9 ohms.
ive dug out some old bits and bobs and have another set of older z1000 coils (both around 3.9 - 4.1 ohms) and another ballast (about 2 ohms).
thanks to help from you im getting to grips with this now but still have a few queries:
what voltage should i be getting between the coil and ballast? im getting 9-10 when running
as the total resistance of my existing system is 4.6 ohms, would it be worth trying my higher resistance (4 ohm)coils without the ballast
if im getting any spark at all then my ignitor and pulse coils are working fine right ?.. so in theory all i need is decent coils, ht's, caps+ plugs with or without the ballast as long as they arnt allowing to much current through the ignitor transistor. get there in the end...

battymatty wrote:

hi, have measured my resistances, coil primary windings are both 2.7 ohms; ballast is 1.9 ohms.
ive dug out some old bits and bobs and have another set of older z1000 coils (both around 3.9 - 4.1 ohms) and another ballast (about 2 ohms).
thanks to help from you im getting to grips with this now but still have a few queries:
what voltage should i be getting between the coil and ballast? im getting 9-10 when running
as the total resistance of my existing system is 4.6 ohms, would it be worth trying my higher resistance (4 ohm)coils without the ballast
if im getting any spark at all then my ignitor and pulse coils are working fine right ?.. so in theory all i need is decent coils, ht's, caps+ plugs with or without the ballast as long as they arnt allowing to much current through the ignitor transistor. get there in the end...

That was what I expected on the coils and ballast. I think Kawasaki originally designed it to not have a ballast. I think Kawasaki found the early batches of ignitors couldn't handle the current they were designed for. To avoid shipping delays and costs of re-making the ignitors, they used a stop-gap measure of throwing on a cheap ballast. Later ignitors did away with the ballast. This is all speculation, though.

As I have said before, I still haven't come across the phantom 1.5-ohm coils that Clymer claims. I think Clymer was confused by the two-stroke Kawisaki's CDI coils which probably were 1.5 ohms or lower.

The readings you get are about right, and your theory of using 4-ohm coils is right.

If you're a gambler, you could even try new 3-ohm coils without the ballast. If it blows up (should not harm new coils) I put a link in my previous post for the DIY ignitor.

You should get at least a good, solid .5 to .74 inch spark in open air to know it's working. (.5 to .75 inch on one side, not both sides). To see that type of spark, you may have to wait til it's dark out or go inside, though, because it's hard to see in sunlight.

Most 3 ohm coils are actually a bit more than 3 ohms. The Dyna coils are generally 3.8 ohms and Accel are about 4.2 ohms. The stockers will be between 3.1 and 4 ohms in my experience measuring these things.

wiredgeorge wrote:

Most 3 ohm coils are actually a bit more than 3 ohms. The Dyna coils are generally 3.8 ohms and Accel are about 4.2 ohms. The stockers will be between 3.1 and 4 ohms in my experience measuring these things.

Every 3-ohm Accel coil I've measured (on 4 different meters) has measured right at 3 ohms.

The many, many, stock electronic ones I measured are always between 2.4 and 2.7 ohms.

WG, based on this and previous posts, I'm starting to think your meter is out of calibration.

thanks again -more usefull info
ive just been tinkering again and found that the voltage between ballast and coils peaks at about 11 volts when revved hard, of course without it im getting up to 14 volts from the charging system, does worry me for the slightly better spark im getting, gonna try the old 4 ohm coils without ballast tommorow and see what happens,
ive also measured voltage between coils and ignitors with the ballast inline, thats peaking around 10 volts (i think -didnt write it down) anyway sure now my problem is with the coils - so if i cant get a decent spark even with the use of silicone and pvc tape then its'll be a set of dyna coils
thanks loads again for helping me understand - getting involved isfar better than taking it to a bike shop....