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08-06-2009, 11:07 AM
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#1 (permalink)
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Always M.I.A.
Join Date: Jul 2009
Location: Alabama
Posts: 2,444
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Dumb Question.....
My dad asked me a question this morning...and stretching my brain's capacities...I can't seem to find an answer.
Here was his question:
"Are the heads in my bike (2009 UGC) and your bike (2009 Rocker-C), 4-valve heads or 2 valve?"
***Both bikes are 96 c.i. "Big Twins".
So, any info would be great. Thanks.
And if there was ever a 4-valve head what model engines had them?
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"The Herd" Member #: 0002
FXCWC: Harley-Davidson Rocker-C
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08-06-2009, 11:10 AM
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#2 (permalink)
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Mentally unstable.
Join Date: Jun 2008
Location: Pennsyltucky
Posts: 6,627
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2 valves per head.
There are aftermarket 4 valve heads on the market for big twins, primarilly for drag racing.
V-rods are the only harleys that have 4 valve heads, however, they're also overhead cammed engines, not pushrod engines.
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HERD meber #10
DISCLAIMER: Any information, advice or child raising tips I give on this forum should be taken with a grain of salt, 8 hours sleep and at least 6 beers.
Following my instructions will likely lead to death, mental retardation and/or bodily injury, consistant with eating lead-based paint chips, and by doing so, will release me, my family and my dog from any legal action(s) for listening to anything I recommended. 
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08-06-2009, 11:35 AM
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#3 (permalink)
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The Northern Redneck
Join Date: Mar 2009
Location: Alaskafornia
Posts: 4,571
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Keep the rubber down & the sunny side up 
You can Sleep when ur Dead...  
Baggers RULE !!!
HERD Member # 000015
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08-06-2009, 11:41 AM
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#4 (permalink)
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Always M.I.A.
Join Date: Jul 2009
Location: Alabama
Posts: 2,444
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Thanks BD...that's the answer I was looking for.
LOL
Dave, thanks again. I knew the V-Rods were, and I told him that they were....He told me to ask on here and see if ours were or not, since they were EFI...
So, they make 4-valver push-rod heads for the Big Twins?
Would they not perform on the street very well? Is that why they're mainly for drag?
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"The Herd" Member #: 0002
FXCWC: Harley-Davidson Rocker-C
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08-06-2009, 11:48 AM
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#5 (permalink)
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The Northern Redneck
Join Date: Mar 2009
Location: Alaskafornia
Posts: 4,571
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[quote=BamaHDRocker;114901]Thanks BD...that's the answer I was looking for.
LOL
Made ya smile....
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Keep the rubber down & the sunny side up
You can Sleep when ur Dead...
Baggers RULE !!!
HERD Member # 000015
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08-06-2009, 11:55 AM
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#6 (permalink)
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Mentally unstable.
Join Date: Jun 2008
Location: Pennsyltucky
Posts: 6,627
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__________________
HERD meber #10
DISCLAIMER: Any information, advice or child raising tips I give on this forum should be taken with a grain of salt, 8 hours sleep and at least 6 beers.
Following my instructions will likely lead to death, mental retardation and/or bodily injury, consistant with eating lead-based paint chips, and by doing so, will release me, my family and my dog from any legal action(s) for listening to anything I recommended.
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08-06-2009, 12:25 PM
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#7 (permalink)
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Can't remember stuff
Join Date: Mar 2009
Location: Williamsburg, Virginia
Posts: 326
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Quote:
Originally Posted by Dave63
More valves....more fuel......more power......
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Agreed on the more fuel part but wasn't the whole idea behind multi-valve engines to increase the intake and exhaust opening sizes but decrease the weight of two really huge valves AND get around the size restriction of the cylinder diameter. Plus, having muliple valves meant that they could allow better flow with less movement, thus allowing for higher RPM without valve float? And...would that really have much of an impact in a relatively low RPM beast like the HD big twins?
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Retired Army 
09 Street Glide
Bolt-on baby!
Herd member # 44
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08-06-2009, 12:54 PM
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#8 (permalink)
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Always M.I.A.
Join Date: Jul 2009
Location: Alabama
Posts: 2,444
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I went to their sight, and Revolution Performance's sight...both offer stuff, but not for my engine...
It shows the 80" Evo "Big Twin", or the "Twin Cam".....Nothing for the 96 c.i. engine...
What is my motor techinically classified as? I thought it was a "Big Twin"...but the only perfermance stuff I find listing for "Big Twin" engines is for 80"ers...Nothing listing 96"...
Is my engine a "Twin-Cam"? They show those as 96" or 97"...
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"The Herd" Member #: 0002
FXCWC: Harley-Davidson Rocker-C
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08-06-2009, 01:02 PM
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#9 (permalink)
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Mentally unstable.
Join Date: Jun 2008
Location: Pennsyltucky
Posts: 6,627
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A big twin is a motor, other then a sporty.
Yes....your's is a twin cam.
96" means it's a 96 cubic inch engine. (Displacement)
Evo's are 80" from the factory. However, can be made larger. I've seen 140" engines.
Those heads can be bought for a twin cam 96" engine.
__________________
HERD meber #10
DISCLAIMER: Any information, advice or child raising tips I give on this forum should be taken with a grain of salt, 8 hours sleep and at least 6 beers.
Following my instructions will likely lead to death, mental retardation and/or bodily injury, consistant with eating lead-based paint chips, and by doing so, will release me, my family and my dog from any legal action(s) for listening to anything I recommended.
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08-06-2009, 01:10 PM
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#10 (permalink)
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Mentally unstable.
Join Date: Jun 2008
Location: Pennsyltucky
Posts: 6,627
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Quote:
Originally Posted by DeepPurple
Agreed on the more fuel part but wasn't the whole idea behind multi-valve engines to increase the intake and exhaust opening sizes but decrease the weight of two really huge valves AND get around the size restriction of the cylinder diameter. Plus, having muliple valves meant that they could allow better flow with less movement, thus allowing for higher RPM without valve float? And...would that really have much of an impact in a relatively low RPM beast like the HD big twins?
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Yes.... by making 2 smaller valves that are lighter, your valvetrain is lighter, and can also move faster and at higher rpms. By having 4 valves, it also makes the head more symetrical, and allows for a more centered spark plug placement, allowing for better firing and power due to a better burn.
having better flow is also a key point and all of which increases power and the ability to produce power. You can't get torque without power.
Having multiple valves has nothing to do with valve float, as how the valve is actuated is more in that department. A pushrod engine with hydraulic lifters will always float a valve before a solid liftered engine, or an overhead cammed engine, just due to geometery and having an oil based (hydraulic) platform.
No...I don;t feel multivalve heads wouldn't have an impact on a street bike used at low rpms, hence my comment regarding them being for mostly drag bikes. For almost $4500 for a kit, for just street use would be a waste. You'd have to change cams with those heads just to feed them, and I wouldn't expect to see performance gains, much over stock, until 4-4.5K on a dyno.....
__________________
HERD meber #10
DISCLAIMER: Any information, advice or child raising tips I give on this forum should be taken with a grain of salt, 8 hours sleep and at least 6 beers.
Following my instructions will likely lead to death, mental retardation and/or bodily injury, consistant with eating lead-based paint chips, and by doing so, will release me, my family and my dog from any legal action(s) for listening to anything I recommended.
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