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Can someone explain to me how adding 120CC to the evolution (2008 models) only gets you an additional 5hp? Or is this a serious derating by H.D.?
 

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No expert here, but the Revo engine is "oversquare"-meaning more bore than stroke. You'll have to add more than 120cc bore to make much difference in total capacity of the cylinder.

Mike
 

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Color me Gone
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Sinister_V said:
Can someone explain to me how adding 120CC to the evolution (2008 models) only gets you an additional 5hp? Or is this a serious derating by H.D.?
Part of it is mufflers and part of it is the fact that the 1250 uses a different set of intake cams so it builds the power quicker and holds it longer instead of shooting for peak HP the way the 1130 does. They have 6 degrees less overlap in the cams. Honestly though if you ever ride a 1250 and then an 1130 back to back the bike that is lighter will win hands down everytime and since most of the 08's have 240s they feel slower then the old 1130cc does.
 

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myvrodrocks
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Sinister_V said:
Can someone explain to me how adding 120CC to the evolution (2008 models) only gets you an additional 5hp? Or is this a serious derating by H.D.?

A 125cc briggs & stratton lawn mower engine is 3 hp...

Does that have any relevance?
 

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myvrodrocks
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HighTechHarley said:
No expert here, but the Revo engine is "oversquare"-meaning more bore than stroke. You'll have to add more than 120cc bore to make much difference in total capacity of the cylinder.

Mike

Not sure where you are going with that...but it deos not matter where you add the ccs - bore or stroke, either will increase the total cylinder capacity...
 

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myvrodrocks said:
Not sure where you are going with that...but it deos not matter where you add the ccs - bore or stroke, either will increase the total cylinder capacity...
But with such a short stroke, will it have much effect compared to a square or undersquare engine? The same bore increase on a longer stroke will have a larger effect on overall capacity.
 

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What?

HighTechHarley said:
But with such a short stroke, will it have much effect compared to a square or undersquare engine? The same bore increase on a longer stroke will have a larger effect on overall capacity.

bore vs. stroke may effect the kind of power the engine makes ( hp vs.torque), but capacity is strictly a function of bore x stroke= CCs ( makes no difference if is oversquare or undersquare, 1250cc is 1250cc).:)
 

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Donwe said:
bore vs. stroke may effect the kind of power the engine makes ( hp vs.torque), but capacity is strictly a function of bore x stroke= CCs ( makes no difference if is oversquare or undersquare, 1250cc is 1250cc).:)
That makes sense. Thanks.
 

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Donwe said:
bore vs. stroke may effect the kind of power the engine makes ( hp vs.torque), but capacity is strictly a function of bore x stroke= CCs ( makes no difference if is oversquare or undersquare, 1250cc is 1250cc).:)
I'm studying your post here and trying to visualize the relationship between bore and stroke.

For instance, if I have two engines of equal bore, except one has a 2"' stroke and the other 4", and I increase the bore on each an equal amount will the gains in cylinder capacity be the same?
 

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Well, using the equation bore x stroke, if you increase the bore on a on an engine with a 2" stroke the same amount as an engine with a 4" stroke the gain in capacity is doubled with the longer stroke. Am I missing something here?
 

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myvrodrocks
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cylinder capacity is measure in volume. to calculate the volume of a cylinder you multiply the radius squared by pi, then multiple by the height.


If you have 2 cylinders with the same bore and different stokes, and you add the same to each bore, the cylinder with the longer stroke will then grow by a larger number.
 

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myvrodrocks
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Donwe said:
bore vs. stroke may effect the kind of power the engine makes ( hp vs.torque), but capacity is strictly a function of bore x stroke= CCs ( makes no difference if is oversquare or undersquare, 1250cc is 1250cc).:)

Bore x stroke does not equal cc's. Radius of the bore squared x pi x the stroke equals cc's
 

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myvrodrocks
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HighTechHarley said:
Well, using the equation bore x stroke, if you increase the bore on a on an engine with a 2" stroke the same amount as an engine with a 4" stroke the gain in capacity is doubled with the longer stroke. Am I missing something here?

I think I am tracking...your comment with that Avatar is making me laugh so hard my side hurts....
 

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All this talk about pie is making me hungry.
 

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Max said:
Part of it is mufflers and part of it is the fact that the 1250 uses a different set of intake cams so it builds the power quicker and holds it longer instead of shooting for peak HP the way the 1130 does. They have 6 degrees less overlap in the cams. Honestly though if you ever ride a 1250 and then an 1130 back to back the bike that is lighter will win hands down everytime and since most of the 08's have 240s they feel slower then the old 1130cc does.
Max, are these cams. the same as the SE Cams, ?
 

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Rollin' Hills
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Whull---OK, but do the younger chicks give a $hit if your stroke is longer---or your bore is increased by a measureable dia.??:spank: :bash: :dance:
 
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