coil + ballast resistor

hi, just tried out coil mod on my z1000 with no improvement, i get 12 volts at the coils anyway while the bikes not firing but this drops to 9-10 volts when running ( though my charging system is working fine), if i bypass the ballast resistor under the tank i get around 12-13 volts at the coils while running and a slightly better spark, what exactly is the function of this resistor, and am i likely to damage the coils by not using it, any ideas- cheers mat

What you are reporting is consistent with how a ballasted system would behave.

The ballast resistor reduces current in the coil at idle and lower RPMs. It protects your points (or electronic ignition) and the coil from overheating. It may not get damaged immediately, but in the long run it may shorten the life of those items.

If your system was designed for the ballast, and you are using the stock coils and stock points (or stock electronic ignition), you should keep the ballast.

As a side note, if your spark energy makes a noticeable change in the way the engine runs, then you probably have fuel mixture issues.

Post edited by: loudhvx, at: 2006/04/24 09:12

Matty, EDIT YOUR PROFILE AND INCLUDE YOUR BIKE YEAR AND MODEL!

Lou stated the purpose of the ballast resistor but I would like to add that as the resistor and the coils age, their resistance tends to increase. Once they get out of spec, your voltage to your coils decreases. In addition, if the coils were swapped with higher resistance coils, the overall resistance will be way too high to get a good spark.

For instance, on my KZ1000E1 project bike, the ballast resistor is supposed to be about 1.5 ohms and the coils about 2.5 ohms. This will give you a total of about 4 ohms resistance and this kept the coils from getting toasty when they were new and allowed them to fire sufficiently to get a hot spark.

With age, the coils primary resistance appears to have crept up to between 3 and 4 ohms depending on which coils is measured and the ballast resistor tests out to almost 3 ohms itself. NOW you have a situation where you have almost double the resistance as the original spec intended and the coils WILL NOT fire a hot spark. A cheap and easy way to "fix" the problem is to remove the inline resistor in this case but it is probably better to buy new 3 ohm Dyna or Accel coils and just not use the ballast resistor. I suspect the aging OEM coils won't work as well as the new aftermarket coils anyway.

He doesn't say the age of the bike, but I have to agree, new coils are definitley a good idea.

Coils gone bad is the only time I've ever been stranded.

will edit my profile next - the bike is a 1980 kz1000 classic converted some time ago from fuel injection to vm33 mikuni carbs when it was imported from the usa to the uk, it has electronic ignition (pulse coils and a kawasaki ignitor unit). im not to worried about damaging the coils by removing the resistor as i intend to upgrade them soon but dont want to harm the ignitor or anything else - can this happen, cheers for all the help.
p.s how fat a spark should i be getting, its now blue rather than yellow but still pretty faint, im used to working on 2 strokes and have always had a fat blue spark in the past.

Removing the ballast will put more current through the ignitor, but I can't say if it would be safe for the ignitor or not. Have you actually measured the ballast resistor's resistance? How about the coil's primary resistance?

If the ignitor blows up, you can make one pretty cheaply.

hi again, so if i upgrade my coils and do away with the ballast resistor would i also need to get an after- market ignitor/cdi unit,
in the mean time im gonna try insulating the coils and top sections of ht lead with silicone and pvc tape to see if im losing power anywhere, still wondereing if the small blue spark is sufficient and all the bogging missing and sooty plug fouling is down to v.badly setup carbs, its likely a combination of problems as per usual and i'll get there in the end- just cant wait to get this beast blatting down the road !!!, cheers again

If you use the green twin output Dyna coils (3.8 ohms), then you can just bypass your resistor which is only inline from the power source to the coils and not the igniter.

You will NOT need an aftermarket igniter. There are none anyway. Dyna sells an aftermarket ignition which replaces both the pick up coils and igniter... the Dyna system has both functions in what appear to be pick up coils. They are VERY inexpensive right now compared to what they used to be... see www.z1enterprises.com - Jeff does ship overseas.

loudhvx wrote:

Removing the ballast will put more current through the ignitor, but I can't say if it would be safe for the ignitor or not.

loudhvx, I think the wiring diagram for a KZ1000 (Z1000) will show the ballast resistor inline with the power source for the coils and NOT the ignitor. The input for the ignitor splits from the source PRIOR to hitting the ballast resistor.

I had a customer come in with an inline ballast resistor that measured about 4 ohms resistance. It should have been 1.5 ohms. He had coils that measured about 4 ohms on one coil and about 8 ohms on the other. Needless to say, he had little spark. Since I looked at the wiring diagram prior to removing the ballast resistor (and subsequently the coils for another set), I am fairly fresh on this subject as it was just a couple days ago. Cheers

your right (on my bike anyway) the ballast resistor is inline with the coils only - effectivly regulating the power directly from the battery to the coils ( however ive noted the power at the coils go up to at least 12.8 volts while firing when bypassing the resistor so its being whacked with some of the charging voltage), the ignitor is on a seperate power source and signalled from the pulse coils, does this mean that if im bypassing the resistor then theres no way i can be harming the ignitor only the coils, thanks for all the interest, its nice to have two kz nuts debating my problem.......

Current from the coils go directly into the ignitor.
If you bypass the ballast, more current will flow through the coils into the ignitor. Ohms law.
Less resistance = more current
The ignitor has to handle more current.

I don't have data on whether that will smoke the ignitor or not. I would need to know the actual, measured resistance on the ballast (clean the terminals to get a good reading). I would also need to know the actual, measured primary resistance on each of the coils to make a guess. Even with that data, it may not be enough for me to guess.

That particular ignitor has been sort of a mystery because I've never seen one or worked with one, and I haven't been able to nail anybody down with actual specs. I trust the Clymer as much as i trust a ... well let's just say I don't trust the Clymer. I find just as many mistakes as I find accuracies in the Clymer. They are good manuals, but they have mistakes in the fine details.

If you don't want to measure it, get new coils and bypass the ballast. It won't harm the coils, but may fry the ignitor. It's only a chance. If you need a brand new ignitor and can connect wires and solder a part or two, you can make one for $30 or so, or buy a used one on ebay for $50 or so or buy a new Dyna ignition for a little over $100 at Z1 Enterprises.

Post edited by: loudhvx, at: 2006/04/25 03:07

I have a Classic also. I was having problems last year with it not wanting to run good a a steady speed. If i hammered on it it ran like a scalded dog.
I started replacing ignition conponents one at a time. I started with the pulse coils. (Kawasaki oem parts)That didn't help so i changed coils(Dyna Green) no help.Then Dyna pulse coils. No help. Changed head this winter. No more intermittent whatever! Must have had the shim tolerance too close.
I ran all the ignition changes through the resistor.
I am now running the stock ignition. I did wired georges ignition relay install and am also running it through the resistor.
I fired it up after the upgrade and it cleared five years of soot out of it.
Just take your time and heed the advice of the members here.
I am currently enegerizing my ignitor off the relay of the coil mod. I'll let you know if it fries.
This in on my LTD.

Post edited by: roy-b-boy-b, at: 2006/04/25 09:03