Velocity Stacks

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darrenmartin
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Velocity Stacks

Post by darrenmartin » Sat Jun 16, 2012 4:33 pm

:wave: Hi guys, ok where do i start?.......Velocity Stacks! :think: :eh: :wtf: is there any chance you guys could do "us mere mortals" a favour and give a "dumbed down" version of, what they are, what they do and if we are thinking of changing them, why we have decided to change em (new jet's, air fillter, high comp piston's,... clutching at straw's coz personaly i really dont have a clue about them) Come on guys give us a clue. Many thanks yet again, coz we realy do appreciate the time and effort you lot take to pass on infomation that for you guys is common knowledge. :thumbup:
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toonarmy
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Re: Velocity Stacks

Post by toonarmy » Sat Jun 16, 2012 4:52 pm

i may get shot down in flames here im no expert but ive changed my short one to a long one which gives more bottom end going the other way gives you top end . they are two black tube type things in the bottom of the airbox lift tank support it and take top off air box then filter out and you will see them you dont need to do anymore mods to go with this although i cut and pulled out the breather pipe that goes into the carb frame while i was on good luck my advice good mod for bottom end/mid range grunt :thumbup: :thumbup:

edds11
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Re: Velocity Stacks

Post by edds11 » Sat Jun 16, 2012 5:04 pm

Darren, velocity stacks, velocity comes from the speed of the air, stacks bit I dont know why they are called stacks, sure mr mon will know why. The way they work is that they are actually attached to the fresh air end of the carb',( in a vtr's case,inside the airbox), and they are used to funnel the air from the airbox and smooth it out, they are also tapered large diameter down to a slightly smaller one at the carb' end, therefore increasing the air speed/velocity hence the name. its all about getting air into the engine a quick and smooth as possible. why does a short one increase top end and a longer one gives more torque :confused . must be the way the air can react to the engines suction and the different lenghts of the stacks.

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darrenmartin
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Re: Velocity Stacks

Post by darrenmartin » Sat Jun 16, 2012 5:08 pm

Hi Toon and tnx for the swift reply :thumbup: I have an idea of what they are about and would recognise one if i was hit in the face with it :) and what youv already said about them is basicaly what i personaly was looking for (info on what or which way to mod or to be told to just leave well alone) its some thing iv never, in all my years of blatting around on bikes, touched on or even given any thought too. Im curious only because after becoming a member of this forum iv never done so much work and played around so much with a bike. Thats down to the solid advice that has been gained from this bunch of reprebates.....yes you know who u are! :thumbup:
Last edited by darrenmartin on Sun Jun 17, 2012 4:28 am, edited 1 time in total.
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rob...
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Re: Velocity Stacks

Post by rob... » Sat Jun 16, 2012 5:48 pm

the different lengths are to do with resonance and scavenging, in the same way an exhaust system works. longer stacks are designed to work at lower revs, and vice versa. on a standard 'storm, at low revs one cylinder is doing more work due to the increased efficiency of it's intake set-up. at higher revs, the other one takes over. two long stacks will give you a little bit more low/mid range, at the expense of a bit at the very top end, two shorts will work better near the red line.
simples. :D
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agentpineapple
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Re: Velocity Stacks

Post by agentpineapple » Sat Jun 16, 2012 7:10 pm

here are my billet long stacks from the good old u s of a...........
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darrenmartin
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Re: Velocity Stacks

Post by darrenmartin » Sun Jun 17, 2012 2:27 am

:thumbup: Thanks for that Edds and Rob i asume then that your Storm has ample "grunt" low-mid rev range due to the higher stack's you have fitted. Could you let me know where you got them from m8.
Thanks for the information on the purpose of the Stacks guy's.My dad god rest his sole always said "if you dont ask , you dont know" and as ever you lot are as eager as ever to pass on and share your knowledge. :thumbup: Many thanks.
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edds11
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Re: Velocity Stacks

Post by edds11 » Sun Jun 17, 2012 8:16 am

velocity stack is an American phrase, we british used to call the Bellmouths, asin the shape of a Bell's Mouth. been used in tuning for years. the same theory can be applied to the length of the inlet tract ( distance from carb' to inlet valve/head). look at old prop'planes and see on them how long the length of pipe from the carb's to the cylinder heads - massive - these things had massive torque and that was how it was gained.

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toonarmy
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Re: Velocity Stacks

Post by toonarmy » Sun Jun 17, 2012 9:09 am

i want them marty nice :thumbup:

rob...
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Re: Velocity Stacks

Post by rob... » Sun Jun 17, 2012 9:35 am

edds11 wrote: look at old prop'planes and see on them how long the length of pipe from the carb's to the cylinder heads - massive - these things had massive torque and that was how it was gained.
true, but they suffered from icing and fuel drop-out.
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cliveyandrews
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Velocity Stacks

Post by cliveyandrews » Sun Jun 17, 2012 9:42 am

Could you let me know where you got them from m8.
I've got an air box on eBay that you could get your second long stack (or try 2 short) - and have a box that you can play around cutting about....


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darrenmartin
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Re: Velocity Stacks

Post by darrenmartin » Sun Jun 17, 2012 3:03 pm

Thanks for the heads up on the airbox u got for sale Clive but i went and bought one this morning for £15 complete with both stack's. Im gunna go with fitting both the Short stack's to gain in the Low - Mid power band. Ill let ya know how it goes :thumbup:
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lloydie
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Velocity Stacks

Post by lloydie » Sun Jun 17, 2012 3:09 pm

darrenmartin wrote:Thanks for the heads up on the airbox u got for sale Clive but i went and bought one this morning for £15 complete with both stack's. Im gunna go with fitting both the Short stack's to gain in the Low - Mid power band. Ill let ya know how it goes :thumbup:
you need both long stacks for low/mid range ....
The short ones will give better top end :-)

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VTRDark
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Re: Velocity Stacks

Post by VTRDark » Sun Jun 17, 2012 3:17 pm

Two long stacks to gain on the bottom end not short mate. :thumbup:

May I also add that the non plastic machined ones add the the extra oomph throughout the whole rev range. Apart from looking the part this is the added bonus to spending a small fortune on the machined stacks.

I have just fitted another OM long stack to mine, so shall report back on performance/feel. I purposely have done no other mods/adjustments at this time so shall no if there is a difference or not.

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darrenmartin
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Re: Velocity Stacks

Post by darrenmartin » Sun Jun 17, 2012 3:26 pm

:thumbup: nice 1 Carl, i await with baited breath........ :wink:
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