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Author Topic: Daul plug bullet  (Read 2201 times)


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Daul plug bullet
« on: July 11, 2008, 03:20:34 pm »
At a bike show I saw a guy with a 96 RE with dual plugs and two coils. The owners dad did the work on the bike and could not tell me how it was done but said the bike started and ran smoother, faster and more mpg. Can any one give me any info on how and why a two sparkplug system works. The second plug was in the decompression valve spot.


  • Grand Gearhead
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Re: Daul plug bullet
« Reply #1 on: July 11, 2008, 04:11:46 pm »
Theoretically you get a cleaner and more thorough burn of the fuel charge, which should produce slightly better power and economy.

This is a very common conversion for older airhead BMW's.
Endeavor To Persevere


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Re: Daul plug bullet
« Reply #2 on: July 11, 2008, 09:46:57 pm »
The performance gain is negligible unless you plan on racing and
your trying to squeeze every last bit that the motor is capible of.

glsgrg is a regular on one of the Yahoo groups. I forget which one off hand.
He did just about every performance mod that can be done, to his Sixty-5
Look close at this pic and youll see the dual coil. It's the light blue bit.
He might be able to help you out.
2008 Bullet 500 Classic AVL


  • Grand Gearhead
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  • you stand tall when you stoop to help
Re: Daul plug bullet
« Reply #3 on: July 12, 2008, 01:25:33 am »
I seem to remember, a long time ago, my friends Husquavarna dirt bike had dual plugs but only one plug wire. He said it was for if the plug got fouled they could just switch to the other. I thought that was a pretty clever idea at the time. Of course now I realize that the "spare" plug would be even more fouled than the hot "primary" plug so I don't know if this was a harebrained idea or if I'm just "misremembering" as our Pres. might say. If I do remember correctly, it was a stock setup. Anyone ever hear of this? I am sure it doesn't really work.
   I understand this really doesn't have anything to do with what you guys are talking about.   


  • Grease Monkey
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Re: Daul plug bullet
« Reply #4 on: July 25, 2008, 09:16:02 am »
I was a user of the old dual plug system in my old Huskies and Montesa MX bikes.
We carried easy a dozen plug in our tool boxes, tool bags, taped to the handle bars!
You get to the start line, start to foul a plug, rev the Pi** out of the bike, hit the kill button as you were reaching for the plug wire, switch plugs and let the button go!
I got so I could do it in the middle of the moto! ;D
I looked at the de-compresson control when I had my Bullet and thought about doing a dual plug conversion.
Me thinks if'n you, 1) mount a second coil, 2) split the wires going into the first coil,  3)a spark plug wire and that should be it.
But, But, But, if you have a electronic ignition system, will it over load it?
Hmmmmmmmm., I'd worry about that part, (seems it wouldn't. It's just a switch, on-engerizes the coil, off, power falls through the windings, making move volts, less amps, poof, out the s/plug wire). If you had a points system, I think you'd be safe(er).
So If'n I was gonna do that, that's how I'd do it.
Me, I leave it alone, maybe get the Bosh coil to give a much hotter, (more volts) spark, a step hotter plug.
Just a constant tinker-er thoughts.
So many bikes-so few $$ :-\


  • Grand Gearhead
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Re: Daul plug bullet
« Reply #5 on: September 21, 2008, 09:43:35 pm »
  Or maybe try a split fire plug, not that I've ever seen any big difference in them, ran them in an old V65 Magna.  They didn't help didn't hurt but didn't foul as easily I guess.  Will.
Will Morrison
2007 500 Military
2000 Kawasaki Drifter 1500
2000 Victory V92SC
1976 Suzuki GT185 Rebuilder Special..AKA (Junkyard Dog)
Many, many other toys.
The garage is full.

speed metal

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Re: Daul plug bullet
« Reply #6 on: October 28, 2008, 12:23:05 am »
hi im new here! im running a dual plug head that i did my self.  super easy. im using a dual output coil and a short reach plug. you have to machine some of the upper sealing surface off the decompressor hole so the plug will thread all the way down and seal on the bottom surface. also plug the small hole that exits to the exhaust pipe. it idles and starts better. not a feel it in the pants performance gain but looks cool.