Dual Plugs or conpression releases

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fatfatboy
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Dual Plugs or conpression releases

#1

Post by fatfatboy » Fri Feb 19, 2010 2:49 am

My STD heads are a dual plug set-up and I am trying to decide if I want to run the dual plugs or compresion releases.
Can some one please explain to me why a dual plug set-up is better than a single plug set-up and how you go about setting up the coil/s (one or two)?



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Re: Dual Plugs or conpression releases

#2

Post by fourthgear » Fri Feb 19, 2010 4:18 am

Well , I will give it a shot . The dual plugs are to give better burning of fuel mixture in the combustion chamber for more power ,HP or whatever .At least that's what they say & may be true to some extent.
You will need two coils & plug wire sets . Unless there is some thing new out there ,that you can run four spark plug wires from a single coil .

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Re: Dual Plugs or conpression releases

#3

Post by Bosheff » Fri Feb 19, 2010 4:21 am

Why in the world would ya wanna run a compression release?....bosheff

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Re: Dual Plugs or conpression releases

#4

Post by Cotten » Fri Feb 19, 2010 4:40 am

Let me shoot too.
Together, our shotgun blast may hit the mark.

H-D OHV domed compression chambers are almost a true "hemi" almost. ("Hemi" = "hemispherical").
But the sparkplug isn't at the top center of the dome.
So to get a more efficient "flame front" of fuel burn, a second plug is crammed in as best it can.

There are variations of ignition timing between the two plugs to get desired effects.
At that point I get lost, and just ask which is cheapest.

Compression releases are for difficult starting conditions.
If you have a physical impairment, as many do, then it should be considered.

Hope this helps,

...Cotten

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Re: Dual Plugs or conpression releases

#5

Post by fatfatboy » Fri Feb 19, 2010 4:47 am

Bosheff wrote:Why in the world would ya wanna run a compression release?....bosheff
I rode an XLCH for 10 years and my knee still feels it. ;)

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Re: Dual Plugs or conpression releases

#6

Post by RUBONE » Fri Feb 19, 2010 5:22 am

As Cotten says the dual plug helps in the burning of the mixture due to the shape of the combustion chamber. It ALSO allows the use of higher compression pistons than are normally recommended for modern fuel. They will eliminate engine knock or "Ping" that would occur with normal fuels and will allow the timing to be retarded slightly for full burn with no knocking. They don't need to fire differently or independently of each other to work. A dual set of dual lead coils is all that is necessary although ignition boosters are available that increase the spark voltage for clean burn. And if you foul a plug your engine still fires on both cylinders.
Robbie
What's a compression release?? :lol:

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Re: Dual Plugs or conpression releases

#7

Post by Bosheff » Fri Feb 19, 2010 5:55 am

I highly doubt that you are going to run a street mill with so much compression that you will need a compression release. A pan motor with 7 1/2 : 1 compression is all that is needed with todays fuel to get the job done, and still have enough power to have all the fun ya want while still havin a dependable and long living engine. I know others will say this is not enough power, but with that compression ratio you won't have to go to exotic ignition systems, and will still be able to get good performance without detenation. Keep it simple and reliable and you will be much happier in the long run....bosheff

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Re: Dual Plugs or conpression releases

#8

Post by Sir_Rat » Fri Feb 19, 2010 9:57 am

Who says you can't have your cake and eat it too??? Just loosen one of the plugs a few turns before starting to allow for compression release and tighten again after the motor starts. Just make sure you stay out of the line of fire if you happen to loosen them too much. :P

HEY JUST A THOUGHT!!

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Re: Dual Plugs or conpression releases

#9

Post by doug_heisel » Fri Feb 19, 2010 3:41 pm

I'm not a mechanic or even that mechanically inclined soI need to ask about this compression release. I have bad knees and at times the old girl just wants to be bullheaded.
but I was under the impression that the fuel had to be under conpression before it would ignite properly. ie exploding in the cylinder and pushing the piston. can you really just loosen a plug and make it alot easier to start? that would be a godsend on some days. And how much damage do you have to do to the heads to install a conpression release?

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Re: Dual Plugs or conpression releases

#10

Post by Bosheff » Fri Feb 19, 2010 3:49 pm

The hot set-up is to use steel braided plug wires, so when the plugs go a flyin, the plug wires will keep em contained so ya don't have to go lookin for em in the bushes....bosheff

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Re: Dual Plugs or conpression releases

#11

Post by NightShift » Fri Feb 19, 2010 5:34 pm

Dear Doug,
A motor will fire with only 45 or 50 pounds of compression which is half of a healthy Pan. The trick is shutting the release real fast.

Dear Sir_rat,
Aint you going to burn your fingers when shes hot?

Respectful,

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Re: Dual Plugs or conpression releases

#12

Post by fatfatboy » Fri Feb 19, 2010 7:51 pm

RUBONE wrote: What's a compression release?? :lol:
Its it that embarassed feeling the day after burrito night. :oops:

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Re: Dual Plugs or conpression releases

#13

Post by fatfatboy » Fri Feb 19, 2010 8:11 pm

doug_heisel wrote: And how much damage do you have to do to the heads to install a conpression release?
Hotbike has some info.
http://www.hotbikeweb.com/tech/0306hb_i ... index.html

Heres a vid on someone doing it to a later head.


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Re: Dual Plugs or conpression releases

#14

Post by hydra74 » Fri Feb 19, 2010 10:53 pm

I have the dual plug set up on my shovel for more then 20 years and the difference with the single plug is not much
gas consumption is the same only in the low revs the engine is running smoother (no single fire)

hydra

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Re: Dual Plugs or conpression releases

#15

Post by doug_heisel » Fri Feb 19, 2010 11:33 pm

fatfatboy wrote:Heres a vid on someone doing it to a later head.
Oh no, Not on my 58 year old heads :cry: My bikes been a good girl just a little stubborn at times, Oh the horrors :cry:

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