Spark Plug Wire Alternative

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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FIRST..... the resistor wire that is used in cars lose too much spark and will not work.
You MUST use plug wiring with solid metalic wire cire.

lol
That's not true. Resistor wire, while not ideal will work fine. Lot of folks have sucessfully used trash scrounged resistor wires.

The problem with solid core wire - it messes with many types of electronic speedos.

We have found Magnecor wire to be the most sensible high perf wire.
 

gubba

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Dec 29, 2008
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jacksonville, florida
The spark plug wire comming from the coil (CDI) requires that the tip of the plug has to be removed fot the connecter to fit over the threads.
Many times I have removed the connecter and found it was still on the plug, having come out of the coil wire. it is near impossible to get it to stay in the coil wire at that point. You end up with the end of the wire just sitting on the plug.
I came up with a very good working substitute, detailed below.
I know that a lot of you guys will find my detailing boring, but remember.... a lot of guys have never done this type of thing.

FIRST..... the resistor wire that is used in cars lose too much spark and will not work well at all.
You MUST use plug wiring with solid metalic wire core. I found everything needed at NAPA Auto Store.

The factory coil wire is 6mm - the smallest NAPA has is 8mm but i'll show you how to make it work.
I used "BELDEN 8mm METALIC PERFORMANCE CABLE - GC". Get 12"... also be sure to get the plug connector (right angle) tip.

Photo 1 shows..... Using a box knife or razor blade 'shave' small amounts of the rubber outer layer off leaving about 1/2 inch of the white inner layer, with the wire in the middle.

Cut wire to length plus a couple of inches.

Photo 2 ...... Strip casing from the other end, leaving about 1/2 inch exposed wire.

Photo 3 ..... Bend stripped wire down as shown.

Photo 4 ..... Place end of wire ino connector and crimp tabs trapping exposed wire.

Remove factory plug wire from coil by 'unscrewing' the wire fron coil (it may be very tight,use a pair of pliers and turn the wire counter-clockwise and remove). DO NOT try to remove by just pulling it out of the hole.
Insert the white end of the new wire (pic 1) by 'screwing' it into the hole turning the end clockwise. Press hard while turning and 'screw' it in tight. It will not fall out.

photo 5 ..... Now you have a spark plug wire that will fit the plug as it comes out of the box, with the tip on ....
 

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Somebody on one of the forums is using regular TV coaxial cable for their spark plug wire.

I suppose bailing wire would work also. That's what they used around the farm on old Model T's when they couldn't find plug wire. ;)
 
I tried some coax cable this morning and the bike ran great!!!
Too bad it scrambled my speedometer and had to be reset. I tried to shield the cable by grounding the outer sheath to the motor, but it was too close to the inner wire an was arcing over and killing the engine. perhaps a rubber hose over the coax wrapped with foil might shield it better without the arcing?
 

gubba

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Dec 29, 2008
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Coax cable does not have enough shielding to elimnate the rf put out by the magneto.
the wire i show does not bother my Schwinn speedo. I have put the adaptation on several bikes with no speedo problems.
 

matt167

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May 20, 2009
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shaving the insulator is not a good idea.. you can cause them to leak the charge to ither ground, or your leg or somthing.. also, the cap should be insulated... not a bad idea, but there are better ways.... Napa, Carquest and a few others have 7mm solid core 'universal sets' I may be able to dig up the P/N for the carquest set... what I used on mine, was a scrap from the set of reproduction plug wires I got for my '51 Chevy.. which are 6mm solid core with a rubber insulator.. just don't expect the speedo to work without a radio supressor.. the wire kit I used the scrap from is $26, so not very economical unless you have a need for the rest
 

gubba

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Dec 29, 2008
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I've used the wire shown for 700 miles and have put it on several biles. It priduces as good or better performance as the original.
It has never 'arced' or zapped my leg. I costs $2.50 TO make.
My NAPA store has never heard of a 7mm solid cor wire in any form.
 

matt167

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May 20, 2009
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I've used the wire shown for 700 miles and have put it on several biles. It priduces as good or better performance as the original.
It has never 'arced' or zapped my leg. I costs $2.50 TO make.
My NAPA store has never heard of a 7mm solid cor wire in any form.
never said it wouldn't work for a while... just you cut somthing down that cracks overtime anyway, so it won't last very long

as for your Napa.. go to a diffrent Napa that knows somthing.. They do sell solid core 7mm. it's just a universal set. there is no car it's tied to..
 

Junster

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Jun 2, 2009
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Rob a iron ferrite ring from anything that has one or get one from radio shack. It's a black steel looking doughnut. Slip the speedo wire thru the middle, slide it up near the speedo mount and slip the wire thru the center a second time. Pull it tight to the ring. That will stop the rf from getting to the speedo. The lump thing on alot of computer wires esp. monitor wires. That's what's under the plastic cover.
 

xlite

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Jun 18, 2009
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ny,ny
i tried 3 diff resistor wires..... all resulted in very reduced performance
Those who understand Ohms Law know that resistor wire is no worse than copper (or "oxygen free" monster wire) in this respect. Any difference is due to damaged conductor or termination and has nothing to do with the material.

Ferrite rings have never helped bike computer resets on the numerous occasions I tried. Unlike resistor wire and shortening which fixed the problem every single time.
 
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matt167

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May 20, 2009
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don't remember the exact ohm of resistor wire, but IIRC it's 3,000 ohms. it's closer to 1,000 ohms on solid core stranded... Supression ( resistor ) wire slows down the electrons so the magnetic feild current around the wires is cut down.. without it, car radio's would just buzz.. but in turn, it adds resistance, with a car that has 10K+ volts the resistance doesn't mean much, but with a low voltage ignition, it does.....


it's also this reason that MSD boxes cannot run with solid core wires. it will damage them
 

xlite

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Jun 18, 2009
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It's true that resistor wire or resistor plugs add resistance. :) There's no big difference between car ignition and bike ignition which is by no means "low voltage". Both must jump similar gaps and produce similar voltage.

It is in fact current which determines the effect resistance will have anyway and 1k, 10k, or even 100k will have less than a fraction of a percent effect in the case of relatively miniscule current.

but in turn, it adds resistance, with a car that has 10K+ volts the resistance doesn't mean much, but with a low voltage ignition, it does.....
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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"Low-resistance" conductors are an easy sell, as most people associate all ignition wire conductors with original equipment and replacement ignition wire carbon conductors (which progressively fail as a result of microscopic carbon granules burning away and thus reducing the spark energy to the spark plugs) and with solid wire zero-resistance conductors that were used by racers with no need for suppression. Consumers are easily led into believing that if a spiral conductor's resistance is almost zero, its performance must be similar to that of a solid metal conductor all race cars once used. HOWEVER, NOTHING IS FURTHER FROM THE TRUTH!
Magnecor Race Wires

What is not generally understood (or is ignored) is that as a result of the laws of electricity, the potential 45,000 plus volts (with alternating current characteristics) from the ignition coil (a pulse type transformer) does not flow through the entire the length of fine wire used for a spiral conductor like the 1 volt DC voltage from a test ohmmeter, but flows in a magnetic field surrounding the outermost surface of the spiral windings (skin effect). The same skin effect applies equally to the same pulsating flow of current passing through carbon and solid metal conductors.

A spiral conductor with a low electrical resistance measured by an ohmmeter indicates, in reality, nothing other than less of the expensive fine wire is used for the conductor windings — a construction which cannot achieve a clean and efficient current flow through the magnetic field surrounding the windings, resulting in poor suppression for RFI and EMI.