Question about ignition coils and resistance/application

[dan filipi]

I tend to not second guess the professional engineers that designed the system.

I completely agree.
I'm not trying to reinvent the wheel but the fact is we're running 25 plus year old ignition technology and there are many improved coil designs out there. Whether an improved coil will work connected to an old primary input design is another story.
I'm sure just the 7mm copper coil wires themselves are a limiting factor.

What I'm after is a compatible set of aftermarket coils since the original coils are no longer available, and if we can boost the spark then all the better.

I found a supplier that has what looks like the same screw type connector for the 7 mm plug wires but 2.5 ohms primary resistance for just $34 each.
https://www.vintagecb750.com/products/5/ ... s-switches
I've found others with over 4 ohms primary for around the same $.

The question remains, will the higher primary resistance work on our 1100's. And if so, are there other changes necessary so we don't burn anything out.

 

[thewhiterhino]

Looking at the diagram for the 83 GL1100A I see the drop resistor that I talked about earlier so that the electronic switches are not switching 12 volts only what ever is left after the resister. I can't remember the E over IXR formulas (too man years since I've used them) but where I'm going with this since the resistance controls the current if it is not matched to the electronic switching devices the actually cause the spark they may burn up from the excess current.
Maybe a whole after market electronic ignition system would be good. My Lincolns, 96 & 97 with the 4.6 engine have coils that have 4 wires coming out but only two coils inside so they will work right for the goldwing as far as that goes, but I have no idea about the suitability of the match of goldwing electronics to the coils but the Lincoln coil receives 12 V direct so it is possible it could overload the goldwing electronics.
:read: :read: :read: :read:
View attachment Towncar coils.pdf

 

[dan filipi]

Intresting the Towncar uses wasted spark coils like ours!
Maybe they could work eh?


Ok, trying to understand the whole thing about resistance without giving everyone a headache. :Awe:

Looking at the secondary resistance,
if the resistance is higher does that mean there must be more coil windings which are causing that increased resistance?
If that is true, does this mean the voltage output potential would be higher?

I ask because the $34 coils have a lower secondary resistance than our 1100 coils but on the other hand they have a higher primary resistance. Just trying to understand the correlation between the 2 and why this is so.

Resistance:
Does lower primary equate to a higher secondary?
Conversely, does higher primary equate to lower secondary?

 

[lew1701]

Hey Dan...is this your coil?



View media item 4529

 

[dan filipi]

Hey Dan...is this your coil?



View media item 4529

Yes that's what the 1100 coils look like.

 

[lew1701]

Hell, I thought I picked the wrong one...anyway, I found a place that has 2 of these in stock, part #30505-MB9-003 ...new/old stock. The price is a little scary ,$124.66 but if it prevents having to redo your whole ignition system.

 

[dan filipi]

Thanks lew.

Mine are cracked but I'm not sure it's affecting their operation but they could be jumping spark to ground when installed.

I'll try the $34 set or run it with the old set before spending that much $ on coils.
For not much more than that we can get Acell coils that far out perform the originals.

 

[joedrum]

it seems that most of the problems of wrong coil match happens on the output side when iwas dealing with the 1000 setup .... it seems to me that the stock setup is not matched with the 1100 ....if it was it wouldnt have a ballist resister in the system .....the 1100s suffered from the same parts bin engineneering that honda used .....this is why the after market electronic ignition were so unquestionly better than the 1000 ignition.....its a same that 1100s didnt have a after market improvement option....ithink that when the ballist resister gose out on the stock coils is when the cdi systems start melting the epoxy out of them....dan the crack in the coil has got to be effecting it somehow ....id say your ballist resistor is bad on your bike ....and replacing the bad coil with another stock coil is the wrong move .....your problem sounds so much like the problem ihad with the 1000 .....replaced cracked coil with new set of stock coils ran better but not good....then started running real bad again fouling plug and stumbleing alot tryed everything new wires caps took resisters out of caps nothing worked .....finaly after thinking there was no way for me to figure it out i went dyna from top to bottom i already had dyna electronic cdi unit by this time and match it with coils and wires and then no more black plug no more anything the bike had never ran so good ever and from there i was able to realy get it to run good ....

 

[dan filipi]

I had to know what effects the cracks in this coil might have so.........

I cut it open.

Intresting it's actually 2 coils in one. I had the impression they were one coil and shared output.

Tiny wire connecting the output tower to the coil center:

Judging by how these things are constructed, my opinion is they will not "leak" spark unless the wire tower is cracked and even then dirt and moisture would have to get in the crack to complete the circuit to ground, and since the tower is a good distance from ground anyway and electricity takes the path of least resistance there would have to be quite a bit of resistance in the plug wire and plug to make a spark take a longer path to ground.

 

[kirkwilson]

Dan,

Back to your basic question about resistance-

Given a equal material, ie, pure copper, pure aluminum, silver or gold, etc- resistance goes up with more windings because each material has a basic resistance dependent on length-

A 1" wire of any material will have less resistance than a 1' wire.

I don't think the diameter of the wire makes much difference in resistance- it just gives you the ability to handle more current. Primaries handle a lot of current- secondaries don't- they are all about voltage to get that arc across the plug gap.

But coils involve a lot more than simple resistance- how they're wound, for example, and they have characteristics like impedence which is resistance but for varying electromagnetic fields- like in a speaker- speakers are rated in ohms just like resistors ( 8 ohms, 4 ohms) but if you put a regular ohmmeter on one you'll get basicly zero ohms. It's the resistance to varying current that gives impedance.

If I was looking to replace my stock coils I would look at 2 things-
I would try and match the primary resistance as close to stock as possible-
And I would look for the highest secondary output voltage rating.

WARNING- I AM NOT AN EXPERT ON IGNITION COILS JUST HAVE SOME BASIC ELECTRICAL KNOWLEDGE !!!!! CHECK WITH THE COIL MANUFACTURER BEFORE BELIEVING ANYTHING i SAY !!!!

 

[kirkwilson]

And I don't think a higher primary resistance would harm the ignition circuit- it would result in a little less current flowing through the primary circuit- everything should work fine. Seems to me that you could get into trouble if the coil primary resistance was lower than stock- that would mean more current flowing throught the circuit and current is usually what burns things up-

 

[dan filipi]

And I don't think a higher primary resistance would harm the ignition circuit- it would result in a little less current flowing through the primary circuit- everything should work fine. Seems to me that you could get into trouble if the coil primary resistance was lower than stock- that would mean more current flowing throught the circuit and current is usually what burns things up-

This is what I'm thinkin also.

 

[kirkwilson]

And just to confuse me somemore as well as probably everybody else trying to keep track of all of this-

Two resistors 100 ohms connected end to end (in series) equals 200 ohms. Two resistors 100 ohms connected side-by-side (in parallel- leads twisted together) equals 50 ohms. So could you connect something like a .1 ohm resistor across the 2.5 ohm primary coil leads to bring the resistance down to something close to .4 ohm? There is a formula to determine exactly what value resistor you would have to use- but I can tell you one thing- it would have to be big- and it would get really hot- there is a lot of current in that primary circuit!

No, that's not right- there's not that much current in that circuit- high current uses big wires - the wires going to my '80 coils aren't that big- so maybe you could use the parallel resistor to match the coil resistance- HEY- Don't we have at least one electrical engineer in this group???????

 

[joedrum]

gee this is way over my head .....but on a purely ignorant common sense view id say a person would have to find out what the value of the coils are that are in the 1100 match that with the ballist resister value and figure out what the value would realy be if the balist resister was not in play ....the ballist resisters get realy hot and the wires are not that bib that feed it and the bike will run when its trashed just not right ....i am correct that the 1100 has ballist resister right i havnt done much to mine and i am going on memory that fails me a lot....on a 1000 the coils are 5ohm with ballist resister...but in reality the stock ignition works on 2.5 ohm coils without ballist resister and when the dyna is used the coils are 3.0 ohm without ballist resister .....when the ballist is out on a 1000 it can be quite a lighting show with spark jumping out of perfectly good wires coils or what ever and will not even run in the rain or super high humidity....i think this is what took out thompson mortor when his bike started running crazy in the rain im no expert but i like the way my bike is set up now because there is nothing in the system between the wire and the coils to fail and cause mismatch ....as far as im concerned the ballist get so hot it cant be good ....even though they dont have any moving parts if it gets that hot it can go bad and dose .....i think this one of the biggest flaws in the wings and cause all kinds of trouble with these bikes just a bad setup from the get go from honda ....ithink all the info on what honda says is right for the 1100 is right for only the mismatch honda did in the first place ....so im inclined to think you have to figure out what the true setup is and when you do it not going to have anything to do with honda specs.

 

[mcgovern61]

Frenchy has replacement coils:

https://www.crescentmooncycles.com/html/ ... coils.html

 

[dan filipi]

Frenchy has replacement coils:

https://www.crescentmooncycles.com/html/ ... coils.html

Those are one coil in question. they are 2.5 ohm primary.

 

[dan filipi]

This is the reply I got from the company selling $34 coils after asking them if these coils would work on a system designed to use .4 ohm primary coils and what would need to be done to make them work, if another or different resistor could be installed.

If you need .4 ohms it will not work. The resistance is in the winding
of the coils and it is not
adjustable.

It's basically a "cover their own ass" kind of answer and doesn't help us any IMO.

So anyway, something for us to chew on.

 

[joedrum]

now that im back home my memory proves itself again .....its wrong almost always....after looking for the ballist resistor on my parts bike ive notice there is none so im under the impression that the 2.5 ohm coils are probably right for the system and coils are matched for the electronic ignition ....so forgive me if im not up to speed on this thread if im not where you guys are at on what your talking about...... :mrgreen:

 

[joedrum]

ive found it dan or somebody needs to go to the NGW site and go to the thread ...something stoleden from the 750 forum .....and post over here the info from the GM hei coils switch .....it looks like the deal for the 1100 ignition setup upgrade that were talking about to get better spark and plug gap ..... :music: :mrgreen:

 

[thewhiterhino]

From the NGF
View attachment 's with GM coils.pdf
View attachment General Motors HEI Ignition Module For Points.pdf