Velocity stacks?

B

BikePike

New Member
So I know it's not classic cafe style, but I'm in between using the stock airbox and going for pod filters, but with the central pods on an IL4 getting less intake than the outer pods I was thinking of just having some small velocity stacks poking out and going to the central carbs.

Question is, they will now have more intake than the outside carbs will I be able to tune them up and balance them well? Or is this a whole new system I'm going into that will need stacks on every carb?

I know it's not traditional and the physics of it is rather tricky but I'm just throwing an idea around here, I think I could make them look good and increase the uniqueness of the bike.
 
Why not use velocity stacks all the way? They won't know if they're on the inside or outside. Not in any way that you couldn't fix with a synch.

If you're worried about your bike eating dust, they make lady's stockings for 'em ;) Not even sure which is more sexy.

(If you're using CV carbs, don't bother with that mess. Keep the airbox and put a more efficient filter on it)
 
Stick with the stock set up.
Crawl before you walk.
Nothing wrong with being new and not knowing things, but no need to get in over your head and hate the hobby.

Know the expression "if you have to ask the price you can't afford it"?
Well in most cases "if you have to ask about a mod then you shouldn't really do it.

Find to experiment.
By all means try things, but know when you are fighting a loosing battle.

There is and excellent Honda manual on the theory of how carbs work.
Might be worth a read.
 
If you plan to actually ride the snot out of it, add a quality filter to the stock airbox. You need to balance the intake pulses/charges on an inline 3, 4, 6 cylinder motorcycle the same as you would an inline 4 or 6 car engine. The air box is ugly, but it works.

Velocity stacks are for the track, even with a nylon mesh pre-screen, you'll draw enough crap through them to damage valves and rings. Save the stacks for engines that are routinely flogged, torn down, refreshed and repeated.
 
Well the idea was to have some filters like pods and have them inside the stacks.

I might just keep the stock airbox with a decent filter and in the future might have a go with velocity stacks on every carb, I'll have a look for that Honda manual.
 
The purpose of velocity stacks is its geometry. Big filters would conglomerate the path of air-flow and thus negate the effects of stacks... But damn will it look cool!
 
surffly said:
Know the expression "if you have to ask the price you can't afford it"?
Well in most cases "if you have to ask about a mod then you shouldn't really do it.
Click to expand...

+1^^ ;D

If you are wanting something unique and different with stacks why not just go all out and make this??: http://www.pipeburn.com/home/2012/11/11/1938-dkw-nz350.html

Otherwise I would just stick with some k&n pods or the like. Don't get the cheap emgo ones, You'll have no fun tuning with those either... Try little mods and slowly until you get to know your bike and how things work. Like mentioned above, if you jump in and try to make an all out custom from the git and only barely touched a wrench previously, you'll lose all interest in bikes very quickly and will be selling a basket case to someone very cheaply.


I6ivKfi.jpg
 
If it's running right, leave it alone! You are opening yourself up to a whole new world hell if you start messing with pods/filters/jets etc. Each carb should have a similar intake, if you are going to change them, for simplicity, use the smaller, good quality filters on all carbs.

Due to the frame I thought the same as you. Mine has bigger pods on the inner two carbs and so are jetted slightly differently.

Took some f'ing about to get the balance right, carbs out, re-jet, bench sync, carbs in, ride, plug chop, check plugs, carbs out, re-jet mains, carbs in, ride, plug chop, check plugs,re-jet pilots, carbs in, ride, plug chop, check plugs,re-jet mains, carbs in, ride, plug chop, check plugs,re-jet pilots, carbs in, ride, plug chop, check plugs,re-jet, carbs in, ride, plug chop, check plugs...you get the idea!

Not only the jets that I had to buy but new gaskets, o-rings and float bowl screws. WOuld have been cheaper and much easier to have bought two smaller pods for the inner carbs!!!

Get the bike looking as near as you want it first. Mine was a rolling resto/custom, best way IMHO as you can still have a blast in between the changes and you can check each change has worked!

BW
 
Redliner said:
The purpose of velocity stacks is its geometry. Big filters would conglomerate the path of air-flow and thus negate the effects of stacks... But damn will it look cool!
Click to expand...

Rubbish. Honda and others incorporate stacks inside the airbox to improve flow into the carbs as it leaves the still air chamber (plenum) that the filter sits in. A well designed airbox not only provides a place to put the filter, but acts as a plenum chamber and silences things.

A well designed velocity stack ( as supplied inside that air box) improves airflow by 2-5% and a bad one drops flow by up to 10%
 
And an airbox that surrounds the velocity stacks is similar to stuffing a filter inside them because...?

BikePike said:
Well the idea was to have some filters like pods and have them inside the stacks.
Click to expand...
 
Redliner said:
And an airbox that surrounds the velocity stacks is similar to stuffing a filter inside them because...?
Click to expand...

I'm not sure what you're trying to get across.

After someone said that stacks will damage the engine because it won't have filters. I was saying it would go through a filter.
 
Putting a filter inside a stack negates the benefits of the stack.
 
Putting a filter inside the stacks though would negate any performance gains you'd expect from them. The reason stacks work is their geometry, accelerating air as it is sucked in, overcoming adhesion etc. Putting any obstruction into this funnel would adversely effect it and you'd end up with no better performance than a pod filter.

If you're new to this and you have CV carbs, do yourself the favor of having an airbox attached. Tuning CV carbs is... I wouldn't recommend it. Nothing wrong with them, you just have to be able to tune something that's so dynamic, whereas slide carbs are manually opened and closed and so not so depending on smooth airflow.

You could put uni-filters on with tin-cans inside to straighten the air as it flows in. Takes a little bit of trial and error but much easier than trying to tune CV's to short intakes.
 
Swivel - is that you?

Large (pod) filters over a correct stack has been done for years and works pretty well on race bikes. Filter inside a stack is not so good - but for some reason seems to work on a TZ750 as long as the "filter" is a wire mesh. Probably because the reed geometry works better with a smaller effective carb cross sectional area.

Pods on some CV carbs are a total nightmare - but not all. In general, they work best with a stock air box.
 
I don't think anybody said filters outside of the stacks are bad. I also think that nobody has said filters inside is good... What's really going on here?
 
Re: Re: Velocity stacks?

Redliner said:
I don't think anybody said filters outside of the stacks are bad. I also think that nobody has said filters inside is bad... What's really going on here?
Click to expand...

As to the latter, I'll say again that it's worse than just stacks.
 
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