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Interesting information regarding airboxes and high flow carbs

This is a discussion on Interesting information regarding airboxes and high flow carbs within the Technical forums, part of the Caferacer.net Forums category; it has got nothing to do with borexstroke the optimum sonic wave tuning is highly dictated by the intake duration an airbox should for the ...

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  1. #11
    Senior Member XB33BSA's Avatar
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    it has got nothing to do with borexstroke
    the optimum sonic wave tuning is highly dictated by the intake duration
    an airbox should for the most part be looked at as not a flow improver but simply a clean place for the velocity stack ends ie the end on the intake port length to be exposed to atmospheric pressure
    this pressurei.hat the waves ,which are firsted generated from the kinectic energy of the intake charge slamm into a closed valve
    the distane to atmospheric pressue,where the wave hits and is reflecto back down the port towards valve is the endresult of the math calculations
    a bonus in my opinion is less intake roar Velocity Stacks, Motorcycle Velocity Stacks, Ram Tubes, Bellmouths hand-crafted by Velocity-of-Sound.com

  2. #12
    Senior Member XB33BSA's Avatar
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    Quote Originally Posted by CaTacL1sm View Post
    I guess the next question is, how to use the CRs velocity stacks while ensuring adequate filtration but allows enough air flow
    a niclely designed airbox with a not hugebut readonable surface surface area filter wont be a flow problem

  3. #13
    Senior Member XB33BSA's Avatar
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  5. #14
    Senior Member Geeto67's Avatar
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    Quote Originally Posted by XB33BSA View Post
    the optimum sonic wave tuning is highly dictated by the intake duration
    Agreed, which is determined in part by cam duration. I mean look at the engine big picture: Stroker engines (undersquare) like a lot of cam duration because the piston has a long distance to travel and the extra volume is in height, vs a big bore engine (oversquare) which doesn't need a lot of duration but prefers larger valves and higher lift cam so as to get the most amount of air volume into the chamber because the increase in volume is in width.

    kawasaki in the 1970's had this nasty habit of making bikes whose optimal power exceeded mechanical redline, and then choked them down to bring the power back in range (you mentioned that earlier). The z1 had something like max hp at 8500rpm stock and a 9000 redline, from my experience with old H1's, they made max torque at 7000 and max power at 7500 stock and had an 8k redline, if you took the airbox off and put foam filters on it the bike would pull hard till it exploded, if you put chambers on it, depending whose design either you pushed all the power further up the range (unbaffled wirges) or you moved it back to a normal powerband range (dencos, 3-1s, etc...)
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  6. #15
    Senior Member CaTacL1sm's Avatar
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    And there's the rub... 99% of the time 99% of riders are at 1/4 To 3/4 throttle.
    Cyorg likes this.
    Quote Originally Posted by alwhite00 View Post
    Fuck all of you guys. Get into your little circle jerk and have fun. Thought this may be a pretty cool message board but damn, you guys are assholes.

  7. #16
    jcw
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    resonance tuning of intake lengths is next level stuff. And frankly, limited to a narrow rpm band anyway.
    I think what we are talking about is more just about adequate airbox volume and adequate intake area to sufficiently not choke the engine at higher rpms. Not hard to grasp.

    I remember even on my 2006 bmw k1200r I had issues. It was designed with a single air trumpet and single filter intake from the front of the bike that narrowed to only about 3 inches in diameter. After opening the airbox with another large opening and filter and removing the restriction in the trumpet, I gained noticeable power from 6000rpms on.

    All engines are different, but they all are basically the same, too. Air in, combustion, air out.


    I wonder what the drag race Kawasaki’s use for an airbox? On a fully faired bike I think I recall reading there is an area of low pressure created behind the engine. But on a naked bike, it might not be so much an issue.
    Last edited by jcw; 01-03-2019 at 11:36 AM.

  8. #17
    Senior Member Geeto67's Avatar
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    Quote Originally Posted by jcw View Post


    I wonder what the drag race Kawasaki’s use for an airbox? On a fully faired bike I think I recall reading there is an area of low pressure created behind the engine. But on a naked bike, it might not be so much an issue.
    enclosed bodywork with ram air inlets at the leading edges of the fairings. They also use short stack trumpets because they pretty much operate in a very narrow rpm range at the top of the tach. Also, Pro stock is mostly suzuki and harley now with kawasaki ducking out a long time ago and the muzzy zx-14 never really getting anywhere.
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  9. #18
    Senior Member Cyorg's Avatar
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    Quote Originally Posted by CaTacL1sm View Post
    And there's the rub... 99% of the time 99% of riders are at 1/4 To 3/4 throttle.
    And IMHO such a large percentage of the $ spent on aftermarket speed parts rob low/midrange in favour of grunt higher up.... assuming they ever get tuned to the point where there is any net gain.
    "Non urinat in ventum"

  10. #19
    Senior Member Cyorg's Avatar
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    Quote Originally Posted by jcw View Post
    resonance tuning of intake lengths is next level stuff. And frankly, limited to a narrow rpm band anyway.
    The Honda CR166 crew would bring along a box full of different length manifolds etc, to use depending on the track.
    "Non urinat in ventum"

  11. #20
    jcw
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    Quote Originally Posted by Geeto67 View Post
    enclosed bodywork with ram air inlets at the leading edges of the fairings. They also use short stack trumpets because they pretty much operate in a very narrow rpm range at the top of the tach. Also, Pro stock is mostly suzuki and harley now with kawasaki ducking out a long time ago and the muzzy zx-14 never really getting anywhere.
    What about the drag bikes of the 80’s? KZ/GPZ, GS. Looks like air tech streamlining refers to a giant airbox as part of the bodywork here.

    DRAG BIKE DRAGBIKE FAIRING AIRBOX AIR BOX BODY ICS FENDER WHEEL TUB BELLY PAN HEADLIGHT UNIVERSAL


    Quote Originally Posted by Cyorg View Post
    The Honda CR166 crew would bring along a box full of different length manifolds etc, to use depending on the track.
    Yes, but I would imagine they would have had the airbox worked out already. Did they even use one?

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