Intake runner length vs velocity stack height

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jarhead
240sx Wannabe
Posts: 137
Joined: Sat Mar 25, 2006 8:39 pm
Location: Denver, CO

Intake runner length vs velocity stack height

Post by jarhead »

Hey guys i am about to get my motorcycle back together and just rejetted the carbs and the wheels in my head started spinning. If you shortened the runner length between the carburetors and the engine but made the velocity stacks longer would this effect the powerband at all. Im not planning on messing with it but theoretically would it change the way the engine runs or am i just trying to reinvent the wheel? I know its neither ka related nor does it have much to do with fab but im not sure where else to post it and theres always smarter people here lol. Thanks
-Jarrod
pa s13
Dont Question My Nissan Knowledge
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Post by pa s13 »

what kinda bike is this first, second if its carbd and not FI the carbs on most bikes sit dam close to the head already just small littler couplers i dont think shortening it that little bit would affect anything if it did, it would not be noticeable. Velocity stacks are designed in motorcycles to flow equally, on gsxr's they end cylinder stacks are taller and middle are shorter, or vice versa been a while since i worked on one, SO in long run no, unless you completely redesign the air box and make it flow more air that way not gona do much
adamky
SuperMod
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Post by adamky »

As long as the overall length is the same, I don't think it will make a difference.
jarhead
240sx Wannabe
Posts: 137
Joined: Sat Mar 25, 2006 8:39 pm
Location: Denver, CO

Post by jarhead »

Thats what i thought. The bike is a 98 zx6r. The later model 6's used a 7mm shorter intake boot from the carb to the head so it just got me to wondering. I figured the closer the carbs are to the head the shorter the runners = more top end and perhaps slightly better fuel mixture at the valve. Like i said its not something im gonna mess with but its something i wondered about. Thanks guys
-Jarrod
jmac636
Knows Some Stuff About 240's!
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Post by jmac636 »

Actually It does create more velocity and has been proven on the dyno by motocross companies like Pro circuit kawasaki. I am a mechanic in AMA Supercross and have been friends with several teams and it is one of the mods that is kept quiet. My brothers race motors have their intakes shortened and adds hp across the whole power band.
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adamky
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Post by adamky »

jmac636 wrote:Actually It does create more velocity and has been proven on the dyno by motocross companies like Pro circuit kawasaki. I am a mechanic in AMA Supercross and have been friends with several teams and it is one of the mods that is kept quiet. My brothers race motors have their intakes shortened and adds hp across the whole power band.
Interesting. Maybe it's worth a try then.
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