more ignition coil info needed

OK...is this forum set up just to sell Accel and Dyna coils?

Or might we have a few guys out there that have tried different coils and had them work?

It's hard for me to believe that those two companys are the ONLY ones that have coils that work...

I just know that on my 79 KZ with electronic ignition (with inline resistor) there has to be another brand coil that works assuming it has a 2 ohm primary like mine.

Or do I have to switch to a points system in order to have a little choice on what coil I use?

C'mon guys...lets not all sell out to Accel and Dyna. Let me hear from the creative bike builders and riders. What other coils work? My local bike wrecking yard has literaly hundreds of coils laying around in boxes. Some of them must work in my bike. Heck, probably MOST of them would likely work if its 12 volt and 2 ohms or more. What do you think?

Bob

well you could always run a mag,not the most practical ignition but i think they look cool! im gonna go through this one and replate everything then figure out someway to dummy it up on my turbo to make it look functional but i will be using a dyna 2000 with 2 sets of coils for the actual ignition.:whistle: :evil:

Post edited by: wireman, at: 2006/10/07 00:22

You can remove the ballast resister and use 3 ohm coils also.

Accel and Dyna are the easiest solutions, but pretty much any coil that will physically fit
and has 2-4 ohms resistance wiil work.

The coils are supposed to be 2.5 Ohms and the ballast resistor 1.5 Ohms. I measured the coils and ballast resistors from both my project STs and the ballast resistors impedence was way higher in both cases... on one it was about 7 Ohms and the other was about 4 Ohms or something along those lines. This left me with coils that had deteriorated so I thought it prudent to purchase an entire new ignition. The least expensive aftermarket unit is the Dyna S and Dyna coils. You can use what you like... the proven Dyna stuff is the best bang for the buck as far as new parts go. You can certainly use any used 3 OHM coil with the ballast resistor removed but used electronics for a bike are like buying used underwear... yeah... it might fit and might work but... ahhhh never mind with this analogy.. You get my point.

Wireman: A mag would be great. But, they take up too much space.

Steell: Accel and Dyna are the most EXPENSIVE solution but that does not always mean its the bestsolution.

WG: My coils measure 2 ohms AND my resistor measures 2 ohms. Those measurements were taken with a brand new digital VOM. The purpose of the resistor is to limit the CURRENT to the coils. Removing the resistor would allow full current to the coils no matter what ohms the primary is. Ohms is resistance. More ohms, more resistance, = more heat in the coil primary.

So it appears there is no STANDARD for 79 KZ's. They seem to have used whatever was available or they may have been trying different combos to get it working right.

My biggest concern is the 'IC Ignitor' which is basically just an electronic switch activated by the pickup coils. It turns on and feeds 12 volts to the coil primarys through the resistor. It's probably not an expensive piece but I don't want to burn it up which is why I am being very cautious in selecting a coil.

But, I intend to go ahead and try some different coils just as soon as I can get back to the motorcycle salvage yard with my VOM and do some testing. I like to save a buck when I can, and there is no good reason for me to use the worlds most expensive coils on my old bike.

It's been too cold to ride anyway...so its time to experiment and fix things that need fixin.

Happy Trails and keep the sunny side up!!!

Bob

Neither I nor Wireman said that Accel or Dyna was the best choice, I said that it's the easiest choice (type in your credit card number, wait a couple of days, take it out of your mailbox and install it).

You have the ignitor description totally backwards, the ignitor does not power the primary side of the coils, it acts just like points do, it grounds the coils and then breaks the ground to cause a spark from the coils.
Disconnect the ignitor ground wire and lose the spark, you'll see

Resistances increase as the coils/etc age.

It's actually less ohms equals less resistance equals more heat, increase the resistance decrease the current and the heat is reduced. Put a 50M resister in the power line to your coil and it will never get hot, of course it won't work either

As far as burning up the ignitor, you can make your own for $30 or so.

Loudvhx's ignitor page

He'll probably chime in sooner or later, he 's the resident electronic guru, I'm merely an assistant

Post edited by: steell, at: 2006/10/07 17:54

Steell: Yep, you did say easiest way.

On the ignitor: Clymer says "An intermediate electronic switch, the battery-powered IC Ignitor, receives the weak signals from the pick-up coils and uses them to turn the ignition coil primary current on and off"

Continuing: "The ignition coil primary current is normally off until the ignition timing rotor approaches the pickup coil. The pickup coil signal builds to a level that turns the IC Ignitor on, allowing primary current to flow through the ignition coil. As the timing rotor passes the pickup coil, the trigger signal reverses polarity and turns the IC Ignitor off. The sudden stoppage of current through the ignition coil primary winding then produces a spark, as in a conventional point/coil system."

IF you increase the resistance of a resistor it gets hotter and hotter. Feel your ballast resistor sometime. Its warm. Increase the resistance and it gets ever warmer. The resistor gets rid of excess current by making it harder for current to flow and that generates a lot of heat. More resistance...more heat.

So...a coil with 5 ohms resistance is going to get warmer than a coil with 2 ohms resistance given they are both supplied by 12 volts (no ballast resistor).

$30 bucks for an ignitor ain't bad. I'll look it over in case I need to get another one. Thanks.

Any how...that's how I understand it..

Bob

You are right that the ignitor turns the coil on and off, but it does it by controlling the ground side of the coils.
Look at any wiring diagram for a bike that uses an ignitor

Kinda hard to feel the ballast resisters on any of my bikes, since none have them, including the two that I have converted to electronic ignition and the one that has electronic ignition stock.

I think Kawasaki only used a ballast resister on one or two models, then only for a couple of years.


Here is a good start to understanding:

OHM's Law

If you want to get really confused, think about why the coils use less power at redline than they do at idle

I forgot to mention, the only coils on KZ's that use a ballast resiter are the 1.5-2.5 ohm coils, the bikes that use 3 -4 ohm coils don't use a ballast resister.

Both of my KZ750 twins that have been converted to electronic ignition (one with 440 parts, the other with 82 KZ750 twin parts) have 3 ohm coils (and no ballast resister).
I could even use the ignitor off your bike on my 750 twin by just using one side of it. The ignitors are basically the same, yours just has twice as many parts as mine because it's for a four cylinder.
My GPz750 ignitor is a different kettle of fish, it has the advance built in instead of using a mechanical advancer like yours (and the 750 twins) does.

As for why you read so much about Accel and Dyna coils on here, have you priced a new coil from Kawasaki? So your choices are:
(1) Replace with another coil of indeterminate age and condition.
(2) Replace with new coil from Kawasaki
(3) Replace with Dyna
(4) Replace with Accel

I prefer the confidence that the coils are not going to fail when I'm far from home that having new coils gives me.
I consider the $120 or so for a new pair of coils to be money well spent. But each to his/her own

Post edited by: steell, at: 2006/10/08 00:51

I think Steell pretty much covered it.

I would just add to what Steell said about the resistance versus heat issue.
One formula for heat is P=(I^2)xR.
That is, the power in a resistor is equal to the current in the resistor squared, times it's resistance.

Assuming constant voltage, cutting the resistance in half would double the current, the result is that the power is also doubled (power correlates to heat). Thus, less resistance creates more heat.

Sorry for resorting to math again.


Also, the Kaw electronic pickups can be used with GM HEI modules. Because of this, I'm going to look into using GM Cavalier coils. They are only $25 or so.

Post edited by: loudhvx, at: 2006/10/08 02:29

Now those were some good answers guys...that's the sort of stuff I've been looking for.

Steell: You're right...I can't afford Kawasaki coils or most any of thier parts. The rest of your reply was great...its info I needed. Thanks

Loudhvx: I'm sorry but saying less resistance equals more heat just does not make any sense. Thats like saying a straight piece of wire is gonna get hotter than hell, and one with a resistor is gonna stay cooler. The wire might stay cooler, but the resistor is gonna get hot. Where's there's resistance....there's heat.

I hope that thing with GM Cavalier coils works out. That's another great example of the type info I was looking for. I'd bet its gonna work. If it said Dyna or Accel on that GM coil it would cost $120.00 or more. And THAT is my point. I shouldn't have to pay $120.00 for a stinking coil. They've been winding coils for over 100 years now and they are basically the same. Its not rocket science. China and Japan can produce them for probably less than $2.00 apiece.

Anyway...great info guys...perfect...

Bob

Bob_79KZ wrote:

Loudhvx: I'm sorry but saying less resistance equals more heat just does not make any sense. Thats like saying a straight piece of wire is gonna get hotter than hell, and one with a resistor is gonna stay cooler. The wire might stay cooler, but the resistor is gonna get hot. Where's there's resistance....there's heat.
.

Bob

You're wire example is out of context.

Hook a piece of wire from the positive terminal on a battery to the negative terminal on a battery. That wire will get "hotter than hell".

On your bike, the wires don't get hot. That's because there is a large resistance elsewhere in the circuit, like a light bulb or coil etc. The 12 volts is being applied to the bulb. The wire only has a few tenths of a volt on it. The bulb is the restriction for the current. A higher wattage bulb has less resistance and definitely gets hotter.

Well, for creativity, I used a Harley Screamin' Eagle coil ($45), a magnetic pickup from a KZ440 and a Mallory Hyfire VIaL for vlotage to the coil. You could get by with just the Harley coil, but it does not mount in the stock location.