V-Twin Coil

[NiteOwl]

I have been having loads of fun riddin the bike, its a 42 EL, the weather has been crappy lots of rain, however the bike runs through it just fine. The other morning I decided it really needed a wash. I washed and shined her, ran it for a minute, she coughed a bit and ran a bit rough, but had an obligation and had to be somewhere with the family.

Anyway, back at the bike about 8 hours later and am having major trouble starting it, once it is running I took it for a ride but it still runs rough and wants to die at idle, I reached down and felt the coil and received a shock. Great. . . I put a heater onto the coil over night figuring something is amiss and it must have gotten wet, more than it should anyway, though the rubber grommets are there and everything seems dry, weird.

My timer cover is absolutely dry no condensation, for that matter my relay is also bone dry. Its 5 am so I can't run the bike up now that I am home from the GraveYard shift, so will have a closer look around noon. (bed now). I thought I would post this asking for any thoughts as to what might be going on. It is a V-twin col and its less than a year old.

Some questions: Is what I am experiencing a sure sign the coil packed it in. Can I dry it? any suggestions? Maybe I should be looking somewhere else, (all my wiring is pretty darn good, even the battery is good and charged.)

[cdndewey]

I read somewhere that with those coils the positive and negative were labelled backwards and if connected like you would be thinking correct it is actually backwards and it shortens the life.

[NiteOwl]

I had read that soewhere too. But surley something so serious would have been addressed over the years.

I wonder, do others hook this up opposite to correspond to the + and - ?

[NiteOwl]

After running the ceramic heater on the coil area for a couple hours, I let her sit overnight. Today she fires up and runs fine. I am guessing something must have gotten wet and to cause the shock on the coil body sure sounds like a short somewhere. Later this week I will reckeck wiring and grounds. At least alls good now and no more baths.

[Sargehere]

I had read that soewhere too. But surley something so serious would have been addressed over the years.

I wonder, do others hook this up opposite to correspond to the + and - ?

Here you go, Bob. I went looking into it and this is what I found:
http://www.caimag.com/forum/showthre...uot-coils-Fail

Note particularly the "Fire Trucks," International Harvester reference, being the most complete.

Along with the enlightened conversation that follows. Hope this helps.

[NiteOwl]

Gerry, what can I say other than Thank You! that is so informative and very usefull information. I am switching my wires around as soon as I get home.

[downunder vl]

Thanks Gerry for that information. We too get the same coils down here and I had my second fail just a few months ago. I had the coil rewound and found that I ended up with a much stronger spark. He did say that he thought that one problem was that the epoxy used around the windings was brittle so that if/when it cracked with vibration etc the winding was broken. He re-packed the rewind with silicon. I'm going to have the second done as a reserve and will take your information to he that rewinds the coils. The case on the first coil was not a real neat job so this time I'm doing the dismantling and re-assembly myself. I do still need to know if there is an easy way to get everything out without damaging the case. I have removed the bottom plate at this stage and that is all.

One thing to watch out for is if the importer of the coils does reverse the positive and negative without notice we will all be back to square one with him selling twice as many coils again, or am I being cynical.

[NiteOwl]

All switched now, starts right up. Hopefully I can extend the life of the plugs and the coil for awhile until I find an original, rebuild. Thanks again for the very useful information, I learned something from this thread.

[D.Mac]

You can also check coil polarity with a volt meter, it's much easier. Set the volt meter to it's highest scale, positve lead to ground, negative to the plug terminal. Kick the bike, ignition on (don't start it) if the needle goes down the polarity is wrong, if it goes up.... you're good to go. The several Tiawan Tedd coils I've checked were indeed backwards from OEM.
Doug.

[c.o.]

Here shortly I will be hooking up a new repop coil. Thank-you for the "easier" way Doug. I'll be giving that a shot.

[downunder vl]

Thanks Doug. I know what everyone who reads this will be doing with voltmeter in hand.

[Hollywood]

I found the easy / easy way. I looked at my coil and saw the little + sign behind the "wrong" terminal. Just switched 'em.

[knuckleheadtim]

It doesn't matter which way you connect the coil primary leads. One plug always fires reverse polarity with a waste spark system, and by reversing the polarity, you're just making the opposite plug fire reverse polarity. You can't compare it with an automotive coil that doesn't have a waste spark; and a coil itself is no more or less effecient when energized in revese.

Maybe the VT coils are just junk! (I can see this is going to be a p--ing match....)

Tim

[c.o.]

I found the easy / easy way. I looked at my coil and saw the little + sign behind the "wrong" terminal. Just switched 'em.

Sure.... state the obvious.....

[Sargehere]

It doesn't matter which way you connect the coil primary leads. One plug always fires reverse polarity with a waste spark system, and by reversing the polarity, you're just making the opposite plug fire reverse polarity. You can't compare it with an automotive coil that doesn't have a waste spark; and a coil itself is no more or less effecient when energized in reverse.

Maybe the VT coils are just junk! (I can see this is going to be a p--ing match....)

Tim

There's more to it than that, Tim! One of the coils, either primary or secondary, is thrown (wound) in the wrong direction, is my information, which reverses the N - S polarity, making the inside of the coil a bit like, in water, paddling up the river against the flow, when compared to the way the coils were designed to work.
Check the International Harvester Fire Truck URL. They specifically address "waste spark." There is just more to it.

Refs:

http://mgaguru.com/mgtech/ignition/ig104.htm
http://www.guy.weatherall.dsl.pipex.com/ht/coil.htm

http://firetrucksandequipment.tpub.c...-14P-1_545.htm