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  1. #1
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    Default coil wiring question

    Ok, I've posted this question on another board to no avail, so hopefully I'll have better luck here. My coil has four wires going in:
    A: Hot
    B: Ground
    C: Front cylinder
    D: Rear cylinder
    My question is can I change the outgoing plug wire placement simply by changing the plug wire input ? In other words, if I run the front cylinder connection from my ignition to the rear input on the coil, will that in turn change the output on my plug wire to correspond? Thanks in advance for any educated assistance in regards to my problem.

    ~Bwagner

  2. #2
    chopped850
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    As far as I know the plugs fire at the same time.

  3. #3
    xllance
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    Ground? You sure?

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    Yeah, if you just have one coil, both plugs should always fire at the same time, even though that means only one cylinder is actually on the compression stroke. So your plug wires should be interchangeable. Is it a stock coil, or an aftermarket brand?

    ~Rev Mike

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    Quote Originally Posted by xllance View Post
    Ground? You sure?
    Lance's point is: most are grounded by the mounting. There is usually a wire from the ignition switch (switched 12v) and the output wire from the points or electronic ignition.

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    You know what would be helpful for an answer?

    1. What year is the bike, or the engine
    2. What coil - single fire coil or not
    3. The ignition -single fire or dual fire, and what brand
    4. What are the coilors of the wires from your ignition to the coil?

    If it's a Harley, you don't have a ground wire, it's probably a tach sender wire.

    If it's a Harley, and it's a dual fire system, you'd only have two wires on your coil (three if it has an electronic tach)

    If it's a Harley, and it's a single fire system, you'll have three wires on your coil from the ign. module (weather it's in the nose cone or not) plus your + lead from your ign. side of your key switch, or wherever you feed it from. The harnass from your ign. module will have 5 wires in it, but two of those wires are the electronic tach lead (which you probably think is a ground wire on yours), and the other is the VOES lead, and they don't need to be connected to have the ignition function.

    And, yeah, if you switch the cylinder signal leads on the coil itself, you can make the front cylinder fire off the rear coil tower, and the rear cylinder fire off the front coil tower, and vice-versa. I do that when I have to orient a coil someplace, and I want the plug wires not crossing themselves going to the spark plugs when I route the plug wires.

    As long as you keep your + lead and the signal wire from your ignition on the "right" lug for your coil type, you can switch the others on their lugs.

    I edited this: If you have a dual fire ignition, and a corresponding dual fire coil, it doesn't matter where you put your cylinder leads on the coil, it fires both cylinders at the same time regardless. A dual fire coil doesn't care where it's wires are hooked.
    Last edited by irishrich317; 03-22-2010 at 11:55 PM.

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    There is no true ground on a coil. Receiving a ground is what triggers the coil. Take a pic of your coil for us. I just posted on someone else's thread the same thing. A single fire coil (2 coils in one case) should have 3 connections. +12v, front trigger and rear trigger. A coil works by taking a charge (12v+ is constant, the negative is provided by ignition module but not constant) When the module puts out a negative the first winding charges, once the negative is gone the charge seeks the nearest ground (your spark plugs), the power in the first winding "jumps" to the plug side (2nd winding) and creates a spark through the resistance in the plugs. A dual fire coil is really 2 coils in one. A standard single fire only gets 12v+ and one trigger from the ignition. A dual gets (1) 12v+ and 2 triggers (one for front cylinder, one for rear). I suppose it's possible you have a single fire coil that takes 2 separate 12v+ and the 2 triggers. But a coil should never have a direct ground. It will interfere with the functionality of the coil. I have never seen a single fire, or dual fire for that matter, with 4 connections. If it does physically say it needs a ground on that wire, it may just be a case ground...... Ok, that's out of the way. No to answer the question (assuming it was working before). Yes, if it is running, and you swap the trigger wires from the ignition and swap the posts that your plug wires go into, you are just switching what side of the coil is firing what cylinder. All that matters is front cylinder trigger fires the side of the coil trying to fire the front cylinder. Hope that helps.

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    Rich beat me to the punch!!!

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    Quote Originally Posted by MileHighMurdercycle View Post
    Rich beat me to the punch!!!
    Yeah, who says old guys are slow????

    Take that, whippersnapper!

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    First let me start off my saying thanks to those that have replied. I left a few details out on purpose so I wasnt chastized for it being a twin cam. it's a 2007 Twin cam that I converted to carb with an Altmann P3 ignition. It's the stock coil and it does indeed have four wires going in. two of which are marked front and rear. The coil also has the output terminals marked as front and rear. My issue is that I've moved the coil location to the top motor mount and the plug wires have to do a criss-cross pattern to reach their respective plugs. I'm simply trying to alleviate the crossing for aesthetic reasons...and to genuinely show my ignorance I'm not sure if the system is single or dual fire....nor do I truly know the difference between those. I'm relatively new to this (five years) and would appreciate any more help you could offer up... Thanks in advance

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    OK, it's a Twin Cam, and it's an Altmann P3 ignition, but you still don't have a ground wire to your coil, and you still only have three wires going to your coil from the P3 ignition module, like I said above. The 4th wire on your coil is the + wire from the switched IGN source, again as I said above . The only ground wire in that P3 system goes from the IGNITION MODULE, not the COIL. And, yes, it's a single fire system, as is the OEM TC ignition, that's how you're able to use an OEM TC coil in the system.

    From the P3 ignition module to your coil (or rather the GM style plug that snaps into your coil) you have:
    1. The white w/black tracer for the center + pole of your coil
    2. The yellow w/blue tracer for the rear cylinder tower
    3. The blue w/orange tracer for your front cylinder

    That 4th wire on your center pole of the coil is the + wire, most guys don't run two + wires to the coil, they splice the two wires together, and run one.

    And, now that I know what you have, I can tell you that you can switch the yellow/blue tracer wire, and the blue/orange tracer wire, and you'll get where you want to be.

    Quote Originally Posted by bwagner View Post
    First let me start off my saying thanks to those that have replied. I left a few details out on purpose so I wasnt chastized for it being a twin cam. it's a 2007 Twin cam that I converted to carb with an Altmann P3 ignition. It's the stock coil and it does indeed have four wires going in. two of which are marked front and rear. The coil also has the output terminals marked as front and rear. My issue is that I've moved the coil location to the top motor mount and the plug wires have to do a criss-cross pattern to reach their respective plugs. I'm simply trying to alleviate the crossing for aesthetic reasons...and to genuinely show my ignorance I'm not sure if the system is single or dual fire....nor do I truly know the difference between those. I'm relatively new to this (five years) and would appreciate any more help you could offer up... Thanks in advance

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    DAAAAYMN IrishRich is one bad muthufucka!!!!!

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    heres the schematic that came with the P3 directly from Altmann:
    Attached Thumbnails Attached Thumbnails P3scheme.jpg  

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    Quote Originally Posted by bwagner View Post
    First let me start off my saying thanks to those that have replied. I left a few details out on purpose so I wasnt chastized for it being a twin cam.
    One thing to consider when posting here, take a look at what folks talk about. No one cares too much what kind/era bike you have. It's about 'owning' it and making it yours. Don't hesitate to provide all the pertinent details. If someone sniped you here for riding a Twin Cam they would get taken to task very quickly I think.

    There are places where you get no respect if you don't have a Panhead and only grudging support for shovels/ironheads. But this aint that place.

    Most everyone here is more concerned with keeping you in the saddle and on the road than what you are riding. Most of us ride and maintain what we can afford, regardless of what cool poster we have on the back of the bathroom door.

    I totally understand your hesitation, but I dont think you need to worry about that on Chop Cult.

    Thanks

    ~Rev Mike

  15. #15
    xllance
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    Quote Originally Posted by revmike View Post
    One thing to consider when posting here, take a look at what folks talk about. No one cares too much what kind/era bike you have. It's about 'owning' it and making it yours. Don't hesitate to provide all the pertinent details. If someone sniped you here for riding a Twin Cam they would get taken to task very quickly I think.

    There are places where you get no respect if you don't have a Panhead and only grudging support for shovels/ironheads. But this aint that place.

    Most everyone here is more concerned with keeping you in the saddle and on the road than what you are riding. Most of us ride and maintain what we can afford, regardless of what cool poster we have on the back of the bathroom door.

    I totally understand your hesitation, but I dont think you need to worry about that on Chop Cult.

    Thanks

    ~Rev Mike
    Mike is right, and my sentiments exactly. But a Big Twin guy hesitant about admitting his bike is a Big Twin to a group largely made up of Sportster guys..............may I just bask in that for a moment?

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