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coil and wires?

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Brendan

Posts: 203

Joined: Sat Apr 04, 2009 7:59 pm

Location: Orlando

Post Fri Aug 07, 2015 7:42 pm

coil and wires?

I have been tracking down an intermittent miss in my ignition system (42 wla). I put an Oscilloscope around the plug wires and noticed a miss fire which pointed me away from a fuel issue.

I decided to get new plug wires and the wires seemed to short out my coil. The original coil wires that came with the coil seem to have an internal resistor. ????? It was a 6 volt coil, now its a hunk of copper.

Anyone experience this. I ordered another coil but I am a little confused as to the configuration for the plug wires.
Resistor or no resistor?

Thanks

Brendan
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Dusty-Dave

Posts: 980

Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Fri Aug 07, 2015 8:21 pm

Re: coil and wires?

Brendan wrote:I have been tracking down an intermittent miss in my ignition system (42 wla). I put an Oscilloscope around the plug wires and noticed a miss fire which pointed me away from a fuel issue.

I decided to get new plug wires and the wires seemed to short out my coil. The original coil wires that came with the coil seem to have an internal resistor. ????? It was a 6 volt coil, now its a hunk of copper.

Anyone experience this. I ordered another coil but I am a little confused as to the configuration for the plug wires.
Resistor or no resistor?

Thanks

Brendan

Plug wires without resistance will lower the voltage at the spark gap which is easier on the coil. I don't know of anyway lower resistance plug wire could hurt the coil. They might lower the firing voltage to a point that the plugs won't fire if they are in bad shape. If you need more voltage to get the plugs to fire a little bit of secondary resistance will raise the firing voltage but be careful its easy to ask for more voltage than a 6V coil can put out. Every time I buy plugs for a 6v or mag bike I check the electrode resistance no matter what the parts house or manufacture says. The wires are short enough on a flatty so that resistance wires don't add too much resistance. At one time you could buy little adjustable spark gaps to put in the coil wire of your oil burner. They would get you buy until you got tired of buying Around the World motor oil!
Dusty
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Brendan

Posts: 203

Joined: Sat Apr 04, 2009 7:59 pm

Location: Orlando

Post Sat Aug 08, 2015 4:58 pm

Re: coil and wires?

Well, I took the originals plug cables off and put the suppressor ones on, the spark was not good and sometimes not there.
I put the Originals back on, which have some resistance per foot, and the spark was strong but again intermittent.
I then put another set of spark plug cables on, with no resistance per foot, and the coil never produced a spark again.

I subsequently found the one of the original cables would open up completely when bumped.

So, It seems I have a pair of cables that have to much suppression, a pair with one acting intermittently, and a pair that will eat my coil.
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knucklebolt

Posts: 434

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Thu Aug 13, 2015 11:04 am

Re: coil and wires?

I've always run non-resistor, solid core wires on every bike I've ever owned, 45, knuck, shovel, K-Model and the Big Twin flathead I have now, and have never had a coil go out. I did have resistor wires on the UL when I first put it together, but threw them away when she wasn't starting good.

I don't think the solid core wires ate your coil.

ken.
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Brendan

Posts: 203

Joined: Sat Apr 04, 2009 7:59 pm

Location: Orlando

Post Fri Aug 14, 2015 12:49 am

Re: coil and wires?

Thanks Knucklebolt
Your post came just in time.
I wouldn't think solid core wires would take out my coil except for the sequence of events that resulted in my coil opening on the secondary.
During my troubleshooting, I could have done something to draw to much from the coil such as open the points with the wire close enough to ground without a spark plug in the circuit.
i just received the new coil and cables that are solid core (no resistance). I am going to install the coil and cables .
Your post gives me more confidence to d so.
Using Champion D16 plugs....

Thanks again

Brendan
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knucklebolt

Posts: 434

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Fri Aug 14, 2015 1:30 pm

Re: coil and wires?

Makes sense to me that a pure points and coil ignition would want as little resistance as possible, although I am not real knowledgeable about electronics. I've also always run solid core wires on all my Mopar hot-rods, and again have never had coil problems.

I have been switching back and forth between the Champion D16 and the AC counter-part, can't really tell a difference. I had been gapping on the small side, close to .025", but just recently opened it up to .030" and it really seemed to wake the bike up as far as easy starting. I've experienced no miss-firing at high RPM. (although "high" RPM to me probably isn't very high") (but I did run her up to 80mph yesterday and she ran fine as ever)

ken.
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Brendan

Posts: 203

Joined: Sat Apr 04, 2009 7:59 pm

Location: Orlando

Post Fri Aug 14, 2015 4:31 pm

Re: coil and wires?

80 MPH???

Engine modified, flywheel Carburetor,???
Are you running regular points or electronic ignition?

Brendan
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knucklebolt

Posts: 434

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Fri Aug 14, 2015 4:47 pm

Re: coil and wires?

My bad, I have a UL, the "Little Mistress" not a 45. Pretty much same engine, 'cept one's a little bigger. :) However, wouldn't 80mph be about top speed for a stock 45, stock gearing?

Here's a pic of the Little Mistress...with the second place Foe Show trophy. !!!

k.
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Brendan

Posts: 203

Joined: Sat Apr 04, 2009 7:59 pm

Location: Orlando

Post Fri Aug 14, 2015 6:03 pm

Re: coil and wires?

Really nice... Tight look without the springer front end. Looks like 4 speed Transmission?

I had my 45 close to 70 (slight downhill) when it blew up. Manifold leak. I was testing it to see if I could hack a ride to Daytona from Orlando for Bike week.

When I get the final tuning done on my WLA I will be looking to start another project. I don't know what yet.

I was going to do another 45 with M249 machine gun Barrels for handle bars, MK19 Grenade Launcher barrels for exhaust, M16 ammo Magazines for pegs, and welded ammo boxes for fuel and oil, the whole thing parkerized, but when I see bikes like yours, I rethink the whole gaudy idea.
I just have all these Army parts in my garage that I want to incorporate into a type of bobber.

I don't know,..... I am looking at engines now. I enjoyed building this one so much I don't see an end at this point. My wife even liked seeing it come together.

Well, my coil came in yesterday and I am putting it on tonight with the plug wires. I'll let you know if the intermittent miss goes away.

Again thanks and nice bike. My next will have to be able to keep up with my friends.

Brendan
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Pa

Site Admin

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Location: Ohio USA

Post Fri Aug 14, 2015 7:08 pm

Re: coil and wires?

knucklebolt wrote:My bad, I have a UL, the "Little Mistress" not a 45. Pretty much same engine, 'cept one's a little bigger. :) However, wouldn't 80mph be about top speed for a stock 45, stock gearing?

Here's a pic of the Little Mistress...with the second place Foe Show trophy. !!!

k.


Ken you know your little mistress is a true beauty. I know it. Wana trade ? Just kidding. I'd love to own your big Twin Flathead but my little ole 45 is damn near all oem.
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knucklebolt

Posts: 434

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Fri Aug 14, 2015 11:54 pm

Re: coil and wires?

Thanks. Yes, 4-speed, she's actually pretty close to stock, although it's built from parts, and the frame is Paughco's close-to-stock frame. They lowered the back-bone for me free of charge, so I would not have that large gap between the top of the engine, and the frame and gas tanks. Most custom frames are made to accept anything from a flathead to an EVO, and will leave a giant gap when using a UL/ULH. I built it to be light and responsive, and have found in the past that a Sportster front end works well on a light big twin. I didn't go springer because I didn't know there were affordable disc brake springers out there....and again Sporter front ends are cheap and easy to find, and work well. The Paughco frame also has a little more rake than stock, otherwise the bike will sit a little high with the longer sporter front end. I wanted the bike to sit low and level. I don't have a weakness for straight line speed, but I sure love corners.

Keeping up with other, newer bikes and friends was not a goal, although if I push the Little Mistress she'll keep up, but I don't. Mostly just enjoy my own ride. I think that if I really wanted to keep up with newer bikes or the OHV's I'd build a Pan or early shovel, something OHV. Just not going to get much RPM out of a flathead. I guess you can go crazy with stroking, cams and all that, but I trust a mild engine more, although it seems many are getting good reliability out of their strokers around here. I do ride with my son on his mega-inch Victory often, and as far as I can tell he doesn't get too disgusted waiting up for me. He usually just follows most of the time, my wing-man, and then goes blasting past me once in a while when I least expect it, to make me crap my pants I suspect. In my own defense, when he does that I can usually catch up to him pretty fast, up to a point.

Pa, you know I'd sure like to own your 45. That would really be something. Especially as a companion to the UL. I love 45's, that was my first Harley...and in fact I set out to build a 4-speed 45 just like it in the beginning, then decided to build a Pan of the same year I was born, and then stumbled on the '37 UL engine. (had I built a Pan, it would be the same as the Little Mistress, except for the engine)

Damn! Not enough life-times to live!

k.
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Cotten

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Location: Central Illinois, USA

Post Sat Aug 15, 2015 7:15 am

Re: coil and wires?

Back to plug wires, Folks,..

I ran shielded microphone cable for two decades, back when braid was cool.
Even cable TV coax has to be better than suppression fiber-core, which made me have to clean my plugs every six blocks.

....Cotten
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knucklebolt

Posts: 434

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Sat Aug 15, 2015 10:50 am

Re: coil and wires?

Ooops sorry about that...got to "plug" the Little M every chance I get, ya know. Besides, she made me do it. And besides that, I had to post that pic to illustrate my solid core plug wires. And too much coffee, and I tend to get "wired".

Hey...braid is still cool. Correct me if I'm wrong, but isn't the entire purpose of suppression wires to cut out interference with radios or electronic devices or electronic ignition? Otherwise, isn't the main idea being to get as much juice to the plugs as possible? Or is there more to it than that?

k.
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Pa

Site Admin

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Location: Ohio USA

Post Sat Aug 15, 2015 12:08 pm

Re: coil and wires?

Logic tells me one really only needs to keep the juice inside the insulation to obtain good spark and at the same time suppress interference. Does that make any sense ?
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Cotten

User avatar

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Location: Central Illinois, USA

Post Sat Aug 15, 2015 12:23 pm

Re: coil and wires?

knucklebolt wrote:... but isn't the entire purpose of suppression wires to cut out interference with radios or electronic devices or electronic ignition?...
k.
Exactly, Ken!

Therefore the shielded microphone cables: I used to ride with a transistor radio in my pocket, and earphones.
It was pointless whenever a chubble with double-plugged heads rode close.

NGK A6 plugs are all now resistors, and foul out in a dozen miles or so.

....Cotten
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Brendan

Posts: 203

Joined: Sat Apr 04, 2009 7:59 pm

Location: Orlando

Post Sat Aug 15, 2015 5:15 pm

Re: coil and wires?

I installed the new coil and non resistive wires. I also installed new points and a condenser. It started right up. I took it for a spin but a severe Florida storm chased me home. It didn't miss once but it was a short lived ride. still waiting for a break in the clouds.


Spark is real strong. You guys lean on the wider gap .030 rather than .022?
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knucklebolt

Posts: 434

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Sat Aug 15, 2015 7:30 pm

Re: coil and wires?

Right on! Brendan Rides again!

I found, just recently, that my engine prefers .030". (yes it's a UL but I think it is closely related enough to a 45) I do have a 12V system, I'm not sure if that helps as far as running a wider gap, compared to a 6V system. However, .030" is within factory specs. On the UL, the gap-range is .025" to .030". My 45 manual says the same, .025-.030".

I had been gapping my plugs at .025-.028", but going to .030" really made it start to start better, with no negative effect(s) that I can detect. In hind-sight, I'm not sure why I chose the tighter gap to begin with. May have thought that I wasn't, or there was a possibility I wasn't getting a strong spark across/at the plugs.

.022" sounds a bit too tight.

I believe, but am not positive, that if you gap the plug too wide, (.030" or larger) you might/may/could get some miss-firing at higher RPM or WOT. If that's the case, then one can just close up the gap until the motor runs normally. but again, .030" is within factory specs, so none of those things should happen.

It would make sense to me, to gap them wide, (.030") and if there's any high speed miss, or missing when the throttle is opened wide, then close them up until it stops.

k.
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Dusty-Dave

Posts: 980

Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Sat Aug 15, 2015 7:31 pm

Re: coil and wires?

Once the field changes either expands through the secondary windings or collapses through the secondary the voltage in the secondary windings builds until it is high enough to discharge or if there isn't enough energy available it builds as high as the available energy allows then dissipates with no spark or a spark some where you don't want it. Most original 6V kettering ignition coils need solid copper wire and non resistor plugs. Magnetos with out a impulse coupling need solid copper wire and non resistor wires. The secondary resistance simply requires more voltage than is available. 12 V kettering systems (points) can use resistance wire but not plugs this will push the spark voltage higher thus moving the RFI ( radio Frequency Interference) above most commonly used bands also producing a hotter spark. 12V switched transistor systems can run resistance wire and plugs. You seldom see CDI ignitions any more because of the incredibly short spark duration isn't suitable for sequenced fuel injection and very lean mixtures, but they work great on our old bikes if you can find one.
Dusty
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Pa

Site Admin

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Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Sat Aug 15, 2015 8:52 pm

Re: coil and wires?

I like setting sparkplug gaps on the tight side of the gap tolerance because I figure as the contacts wear the gap opens up anyway.
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knucklebolt

Posts: 434

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Sun Aug 16, 2015 12:15 am

Re: coil and wires?

I thought of that too, but as I constantly fuss over the bike anyhow, re-gapping the plugs as often as it takes, or often, is okay with me. I probably pull them every couple of hundred miles just to take a look to see if they are sooty, or not sooty....or whatever.

If one prefers to set the gap, and not mess with the plugs unless necessary, for sure one would probably want to set them tighter. One too many cups of coffee, and I'm out in the garage pulling the plugs anyhow. !!!! :shock: There's my too much coffee face in fact.

But the question is....have you (or anyone) ever noticed any change in how easy the bike starts, depending on the gap? I may be wrong, possibly just a coincidence, and Little M was well on her way to normal starting before I did it, but when I opened my plugs up to .030", seems like she really fires up fast. ???

k.
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