about those spark plugs

**jestephens** · 10-21-2009, 08:37 PM

I just read a recent post about our spark plugs in the Garage forum, and it reminded me of a question I wanted to ask you all.
::)
Why 4 plugs in a 2 cylinder engine? My first presumption was for twice the spark thus a more efficient burn and power . . . . BUT THEN someone told me that one set fired on the exhaust cycle in order to burn any remaining fuel thus reducing emissions.

So which is it? Or maybe something really cool I don't even know about ;)

**ringadingh** · 10-21-2009, 08:43 PM

The plugs fire at the same time in the cylinder, its an easy way of getting a better burn in a large displacement motor. We only have two coils, one for each cylinder. If you wanted to fire the plugs independently you would need a separate coil for each plug or a distributor.

blowndodge · 10-22-2009, 01:21 PM

Dual flame fronts allow the burning mixture to travel through the "squish" area more efficiently thereby allowing more advanced timing without detonation. As you can see it doesn't work worth a sh*t on the Nomad.

This wouldn't be needed with more centrally located spark plugs.

**glwilson** · 10-22-2009, 01:45 PM

Quote:

Originally Posted by Blowndodge "Darksider"

the "squish" area

The "SQUISH" area... now... that's a technical term -- right?

snarleybill08 · 10-22-2009, 01:59 PM

they do all fire on the exaust stroke but not for any reason benefitting the engine. it is so they don't need a distributor. a whole lot of engines do this. even lawn mower engines. firing on the exaust stroke has no benefit whatsoever, and it will shorten the electrode life of the plugs. bill

10-22-2009, 02:38 PM

Quote:

Originally Posted by jestephens

I just read a recent post about our spark plugs in the Garage forum, and it reminded me of a question I wanted to ask you all.
::)
Why 4 plugs in a 2 cylinder engine? My first presumption was for twice the spark thus a more efficient burn and power . . . . BUT THEN someone told me that one set fired on the exhaust cycle in order to burn any remaining fuel thus reducing emissions.

So which is it? Or maybe something really cool I don't even know about ;)

Its got a technical name (lol). Its called "wasted spark ignition".

the front pot and rear pot all fire together, so when the front is on compression and needs the spark, the rear is on exhaust and the spark has no use at all. As bill says it saves on a distributer, keeping build costs down. But Plugs will still work for over 30,000 miles if you want them to. ::)

blowndodge · 10-22-2009, 05:11 PM

Quote:

Originally Posted by glwilson

Quote:

Originally Posted by Blowndodge "Darksider"

the "squish" area

The "SQUISH" area... now... that's a technical term -- right?

Ok Harley turncoat!

"squish band" measured in width and angle from the outside edge of the head as related along the head plane to the sparkplug. This band length and angle are used to create "turbulance" inside the combustion chamber for better flam propagation.

Now get back on that leaky Harley and ride!!

**glwilson** · 10-22-2009, 09:10 PM

Quote:

Originally Posted by Blowndodge "Darksider"

Quote:

Originally Posted by glwilson

The "SQUISH" area... now... that's a technical term -- right?

Ok Harley turncoat!

"squish band" measured in width and angle from the outside edge of the head as related along the head plane to the sparkplug. This band length and angle are used to create "turbulance" inside the combustion chamber for better flam propagation.

Now get back on that leaky Harley and ride!!

It's too cold out... I only ride when it's "comfy"!!!

;)

**Top Cat** · 10-22-2009, 09:32 PM

What, he rides a Harley and he's still an Ultimate Member

;)

**schoeney** · 10-22-2009, 11:31 PM

Greg bought a Harley?...oh no...now he is a 99 percenter!

Next thing you know he will be wanting to grow the federal government, support the entitlement programs, bailouts, and help B.O. (I love calling him B.O....because he stinks!) run for re-election!

**glwilson** · 10-24-2009, 03:09 PM

See what you started BD!!!

I fessed-up to the purchase the week I did it in late July. I stepped-down from being an ARL of the NC Region. Trip allowed me to hang around anyway.

Regarding entitlements, bailouts, socialism, and that kind of crap... you can count on me to not support that.

HOWEVER.. regarding "BO" -- I like that! ;) That's what I'm going to start using from now on.

So... in conclusion... all of you guys watch your plugs when it concerns the "squish" area!

**Kawhead** · 10-24-2009, 04:21 PM

Quote:

Originally Posted by Blowndodge "Darksider"

Quote:

Originally Posted by glwilson

The "SQUISH" area... now... that's a technical term -- right?

Ok Harley turncoat!

"squish band" measured in width and angle from the outside edge of the head as related along the head plane to the sparkplug. This band length and angle are used to create "turbulance" inside the combustion chamber for better flam propagation.

Now get back on that leaky Harley and ride!!

Now that ^ was a squish!

AlabamaNomadRider · 10-24-2009, 10:55 PM

Squish is a good sound when you are really having fun.

skeeter · 10-24-2009, 11:23 PM

Can you squish your pics together so your harley will fit on my screen.

Where was the picture of the Harley taken? Do you have any pics on photobucket?

**Top Cat** · 10-25-2009, 12:21 PM

Quote:

Originally Posted by skeeter

Can you squish your pics together so your harley will fit on my screen.

Where was the picture of the Harley taken? Do you have any pics on photobucket?

Yeah Greg, I wasn't going to say anything but now that skeeter brought it up.
Could you stack one of your sig pics so some of us don't have to scroll left to right to read any thread you post in?
I know you guys get sick of my whining but damn, it is annoying when the screen is made to wide by over sized pictures.

10-21-2009, 08:37 PM	#1
jestephens Join Date: Jan 2009 Location: Fairview Heights, IL (StLouis) Posts: 1,601	about those spark plugs I just read a recent post about our spark plugs in the Garage forum, and it reminded me of a question I wanted to ask you all. ::) Why 4 plugs in a 2 cylinder engine? My first presumption was for twice the spark thus a more efficient burn and power . . . . BUT THEN someone told me that one set fired on the exhaust cycle in order to burn any remaining fuel thus reducing emissions. So which is it? Or maybe something really cool I don't even know about ;) __________________ Jay Stephens, Former National Vice President (2013-2015) 2006 Yamaha FJR1300 formerly 2011 Vaquero- Black formerly 2005 Nomad - black/silver Login or Register to Remove Ads
	0

10-21-2009, 08:43 PM	#2
ringadingh Join Date: Aug 2007 Location: Newmarket Ontario Canada Posts: 35,387	about those spark plugs The plugs fire at the same time in the cylinder, its an easy way of getting a better burn in a large displacement motor. We only have two coils, one for each cylinder. If you wanted to fire the plugs independently you would need a separate coil for each plug or a distributor. __________________ 2002 Nomad aka Bountyhunter VBA #27 VROC #18951
	0

10-22-2009, 01:21 PM	#3
blowndodge Sr. Contributor Join Date: Jul 2007 Location: Washington City, Utah Posts: 16,474	about those spark plugs Dual flame fronts allow the burning mixture to travel through the "squish" area more efficiently thereby allowing more advanced timing without detonation. As you can see it doesn't work worth a sht on the Nomad. This wouldn't be needed with more centrally located spark plugs. __________________ I love my Victory Cross Country Tour 106. Smells like Victory! Ultra's are Limited There are two types of Harley riders. Those that trailer them and those that push them. The most Interesting Man in the World* "Find the things in life you don't do well and don't do those things" Member # 0005
	0

10-22-2009, 01:59 PM	#5
snarleybill08 Member Join Date: Oct 2009 Posts: 273	about those spark plugs they do all fire on the exaust stroke but not for any reason benefitting the engine. it is so they don't need a distributor. a whole lot of engines do this. even lawn mower engines. firing on the exaust stroke has no benefit whatsoever, and it will shorten the electrode life of the plugs. bill Login or Register to Remove Ads
	0

10-22-2009, 09:32 PM	#9
Top Cat Join Date: Jul 2007 Location: Peoples Republic of New York State Posts: 15,154	about those spark plugs What, he rides a Harley and he's still an Ultimate Member ;) __________________ Tim "TC" Conley VBA #9 2011 Victory Kingpin mine 2013 Victory Boardwalk -hers [LEFT][COLOR=#000000] [SIZE=4]
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10-22-2009, 11:31 PM	#10
schoeney Join Date: Jun 2008 Location: NW Region Posts: 5,222	about those spark plugs Greg bought a Harley?...oh no...now he is a 99 percenter! Next thing you know he will be wanting to grow the federal government, support the entitlement programs, bailouts, and help B.O. (I love calling him B.O....because he stinks!) run for re-election! __________________ VBA #659 2003 Nomad 1500 (Gone but never forgotten) 2005 Honda ST1300 - Sweet and still kickin 2006 Honda Goldwing - Best Boat in the Marina
	0

10-24-2009, 03:09 PM	#11
glwilson Join Date: Jul 2008 Location: North Central Illinois Posts: 8,575	about those spark plugs See what you started BD!!! I fessed-up to the purchase the week I did it in late July. I stepped-down from being an ARL of the NC Region. Trip allowed me to hang around anyway. Regarding entitlements, bailouts, socialism, and that kind of crap... you can count on me to not support that. HOWEVER.. regarding "BO" -- I like that! ;) That's what I'm going to start using from now on. So... in conclusion... all of you guys watch your plugs when it concerns the "squish" area! __________________ "During times of universal deceit, telling the truth becomes a revolutionary act." "You can have your own opinion, but not your own facts." *Former VBA NCR Assist Regional Leader* Formerly: 2004 1500FI Bronze Nomad: 2009 & 2014 HD Ultra Current Rides: 2017 HD Ultra Limited & 2011 Can Am Spyder RTS-SE Attended: VBA National Rallies 2009, 2011, 2015; VBA/NCR Regional Rally 2010, 12, 14, 16 and several rides throughout with regional members. VBA Member #652 HOG Member #3935417
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10-24-2009, 10:55 PM	#13
AlabamaNomadRider Sr. Contributor Join Date: Jul 2009 Location: Boaz, Alabama Posts: 13,742	about those spark plugs Squish is a good sound when you are really having fun. __________________ Gene Cross, Jr. Boaz, Alabama KawaNOW/VBA #1181
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10-24-2009, 11:23 PM	#14
skeeter Sr. Member Join Date: Mar 2008 Location: Kerrville Tx Posts: 1,713	about those spark plugs Can you squish your pics together so your harley will fit on my screen. Where was the picture of the Harley taken? Do you have any pics on photobucket? __________________ Robert(skeeter)Dozier 07 Red&Titanium Nomad 81 Suzuki 850GL KawaNow pre#
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