velocity stacks
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Thread: velocity stacks

  1. #1
    Fuelled by rice Array racerboy88's Avatar
    Join Date
    Apr 2002
    lower mainland

    velocity stacks

    Hey guys,
    Been hearing a lot about graves velocity stacks and I just wanted to know what exactly do they do for the bike?
    02 R1- stolen Nov 24/02

    Hang Thieves

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  3. #2
    Its quiet in here! Array Biker69's Avatar
    Join Date
    Nov 2002
    1993 CBR900RR
    Velocity stacks replace the airbox and airfilter, they are tapered tubes that sit where the airbox used to go, you get a tad more power but I think there installed more for tuning convenience as its easier to get at the carbs. Only for race bikes only as the engines are rebuilt often, If used on a street bike, be prepared to overhaul your engine after the riding year is over. Plus there is a chance you can suck in a rock and do serious engine damage!!!!!
    Head tech inspector-WMRC

    2000 GSXR750 racebike for sale-

    Team Black Dog Racing

  4. #3
    In my opinion Graves Velocity Stacks are the most cost efficient way to get can get 5-7 HP with them...they cost around $90...not bad at all...this is on a 2002 R1. Once I decide on a new exhaust I am gonna pick up a set. Hindle BDE Ti system or a Akra Evo system with Graves Velo stacks a PC3 and your into GSXR1000 territory then add a Graves or Hotbodies racing Ram Air kit and your making more HP than a GSXR1000...

  5. #4
    its closer now Array SILVER_6R's Avatar
    Join Date
    Sep 2002
    closer than you think
    NONE--911 C2

    if you are considering putting velocity stacks on a street bike ESPECIALLY a carbureted one.... BE PREPARED FOR CONSTANT TUNING!!

    we use velocity stacks as a tuning device... different lengths can change your power curve, but this also requires tuning. Yes, you will gain power but are you prepared to getting a bike that is that more sensitive to atmospheric changes (temp, humidity, altitude).

    anyways... IMHO... not a good choice for street bikes.
    R.I.P. Dan and Cody

    Forever in my mind, forever in my thoughts, forever in my heart

  6. #5
    Registered User Array newbusa's Avatar
    Join Date
    Oct 2002
    Qualicum Beach
    Ktm 1190,ThruxtonR 1200'Drz4

    Thumbs down

    I used to have velocity stacks on my dragbike but it was a track only bike would i have them on a streetbike ?No way!you have to have some filtration between your engine and the crap out there.If you want to put them on your bike be prepared to buy a shop manual you will need it.

  7. #6
    Registered User Array Jumby's Avatar
    Join Date
    May 2002
    North Van
    Zx6 07, Crf 450r, Yz250f
    My 2 cents: when u add length to ur intake by adding stacks u change the time in which ur pressure wave hit ur intake track, at certain RPM it will give u a noticable boost in torque, but at different RPM it will do the opposite.This is not BS, it is the truth, in the WSB tuners have special servo motors that change the intake length to accommodate different RPM, the same principal is applied in F1 cars. I don't disagree that u will get a boost in power, but u will have just got a real nice flat spot some where in ur power curve.

    This is what happens when ur piston fires, a positive charge flows down the exaust pipe (and we all know that with a positive, there at some point will be a negative sign wave) behind that positve pressure pulse is a vacume. Now in ur motor the is a time where both intake and exaust valves will be open, this time is called overlap. During this time (overlap) that vacume goes through the exaust valve into the cylinder then through the intake valve up through the intake track, this helps charge ur cylinder with air and fuel before ur piston has started on it intake stroke. Now that situation doesn't happen like that all the time RPM will change that. This is where it gets tricky, when u ad length to ur intake u change the time it takes for that negative sign wave to travel through ur intake system. Now the length is longer, at higher rpm that sign wave wont get there when it did before, the positive sign wave gets there when it should be a negative, this causes ur motor to get a nice ugly flat spot. U exaust system also has alot to do with ur intake length to but I wont go into that.I don't like typing all that much.

    I don't want to deter u from doing it, I think u should, It would be a great learning experience. What I would do, is go to a dyno that has a EGA, run the bike before u do any work to it, get the fuel/air mix ratio. Then put on the stacks go back to the dyno and see what happens, u might be supprised or u might be disappointed iether way it should be fun. Also make sure u do both dyno runs on the same dyno. And don't go by what the company who sells the product claims it will do, it rarely ever meets those claims. I am not real god at writing so please don't come down on me to hard about my grammar and spelling.

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