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Senior Member
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2,505 Posts
Looks like he's a former member here, hadn't been on since April. Hopefully he'll come back.
 

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Crowley
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1,263 Posts
Aerodynamically speaking, is it detrimental to have unequal runner lengths for the intake tubing? Would the ideal setup include two equal length runners? Why or why not?

I think I'll be next to try this.
 

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2014 KLR 650!
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3,361 Posts
I would think the angle it peals off the stream is more detrimental. But like I've said before, my sportster is one carb and should be no different for the VN.
 

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Crowley
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1,263 Posts
I'm just trying to understand, because my knowledge is limited here, but if it's 6" from throat to front cylinder boot, and 3" from throat to rear cylinder boot, would it perform poorly compared to equal length?

So the piston draws air through the carb on the intake stroke, which causes it to pass by the needle and other jet openings, causing a venturi effect, dragging fuel out.

I'm left to believe that from the jet/needle area to the cylinder, the entire volume is filled with air/gas, which indicates to me length wouldn't matter.... But...

If we made this an extreme example, if we have a 2" runner and a 2' runner. Wouldn't the 2' runner cylinder exert more force to pull the same amount of air from the filter, through the carb?
 

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ass hole extaordinaire
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3,780 Posts
I will check the banned list tonight and see whats up the guy went by honest al on here too
 

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FREEBIRDS MC CENTRAL NY
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16,076 Posts
Don't think he was banned.think he was warned and said he was quiting
 

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Crowley
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1,263 Posts
Just going by what he said. And goofy, the reason for such an exaggerated example was to accentuate any theoretical problems - - if runner lengths are near equal, any aerodynamic flaws would be hard to detect. Exaggerate those conditions and the symptoms become more prevalent (in theory)

I'm wondering about the force needed to draw air through all that length, and if that would affect performance
 

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Registered
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1,021 Posts
I would think, much like water, once the flow started it should be equalized at point of entry to the cylinder. Initially, it may take a second longer to initiate but once started the flow would balance out based on the vacuum draw exerted by each cylinder. ?
 

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Chasin' the blacktop
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1,498 Posts
Sweet setup, Car manifolds usually have unequal runner lengths and they work fine. I bet that if he made up a set of 10 manifolds they would sell well on this site.
 

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Dr. Vulcanstein
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1,536 Posts
Just an opinion, maybe people are trying too put to much rocket science into what I thought was a motorcycle and all the math and equations are intimidating ones attemps? What happened to trial and error?
 

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Crowley
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1,263 Posts
Jada, I see your point. Any flaws the intake may have could be insignificant. I'm always fond of being able to make something work most efficiently... So if I can gather as much info beforehand, I'll hopefully have less trials and errors lol.
 

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Dr. Vulcanstein
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1,536 Posts
Jada, I see your point. Any flaws the intake may have could be insignificant. I'm always fond of being able to make something work most efficiently... So if I can gather as much info beforehand, I'll hopefully have less trials and errors lol.
Roger that. And know I didn't mean any negative by that post, just trying to say sometimes people try and use too much mind. Sometimes its when ya kick back a sec an the shyte falls in your lap. You know what I mean bro.
 

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FREEBIRDS MC CENTRAL NY
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