Topic: adding foam to velocity stacks

[KeithB]

If this is an "all show no go" bike then ignore this post.
However, if you actually are looking fo the go, then run them open or just coarse screen.
The whole point of a properly tuned stack is to improve the air flow characteristics to the carb for better performance.
To actually be effective they need to be tuned for the carb settings and exhaust system.
To put and air filter in the way of the incoming flow seems counter productive.
These are generally used on the track where high performance for  short periods is needed and engine re-builds are common.
Might as well use pods.
Just my $.02 worth...

[greenjeans]

To be honest, It would probably only get about 15-20 miles during the week total (short commute)
with the occasional weekend ride to shows etc.  Usually once in the summer I'll take a trip on
it (still, not more than about 250 miles or so) and realistically that's about it.  No trips to the
track, mainly just short cruises....probably spend more time warming her up than riding.
Just always love the looks of a velocity stack.  I'll start by running the fine mesh screen and
maybe I'll experiment with some thin foam...who knows. 

[James]

Running filters on stacks is  like taking your Mom along when you go on a date..

In some places they are the same person

Be mindful that there is a hell of a lot of suck going on at the stacks, a pal o mine put some foam over the stacks and after his first ride found some nice neat holes in the foam, the bike still ran, but I'm not sure that it did it any good.

I would say put a metal screen between the foam and the carbs to give it a bit more integrity!, or get some proper K&N foam, not just household stuff.

[eldar]

How fine are your screens? I mean if they are not that fine, Get some different screen material that has smaller openings. Still wont filter like foam or paper but will stop some smaller stuff.

[754]

I actually think fine screen would be quite restrictive...

The main problem is lack of area to filter, unless you use very thin foam and a coarse screen, after a point the overall flow gets reduced. and I dont think thin foam will stop everything.

Here is another example, I took the ends of UNI filters or other such foam, put it over the aircleaner end of CB350 carbs..it was so restrictive it barely ran.. so the bigger the aircleaner the easier it breathes. I was sa bit surprised when the first tapered K&N's came out, still dont know if it was for less interference on the outer end or for turbulence reasons of airflow past the outer aircleaners.

In my mindseye, I see this with very fine screen.. imagine pasta being pushed thru a fine screen.. as it comes out the other side it would be all squiggly and curling  and twisting.. anything but straight. This is what I am thinking happens to the air when it hits the screen.. instead of a smooth coloum of air entering it is a jumbled mess of a thousand small coloums of air trying to straighten out and join together.

But the screen will keep flies out!!

It takes quite a while to wear out the topend on an unfiltered motor.. unles you live in extreme dusty conditions..longer than you may think..

[goon 1492]

I actually think fine screen would be quite restrictive...

The main problem is lack of area to filter, unless you use very thin foam and a coarse screen, after a point the overall flow gets reduced. and I dont think thin foam will stop everything.

Here is another example, I took the ends of UNI filters or other such foam, put it over the aircleaner end of CB350 carbs..it was so restrictive it barely ran.. so the bigger the aircleaner the easier it breathes. I was sa bit surprised when the first tapered K&N's came out, still dont know if it was for less interference on the outer end or for turbulence reasons of airflow past the outer aircleaners.

In my mindseye, I see this with very fine screen.. imagine pasta being pushed thru a fine screen.. as it comes out the other side it would be all squiggly and curling  and twisting.. anything but straight. This is what I am thinking happens to the air when it hits the screen.. instead of a smooth coloum of air entering it is a jumbled mess of a thousand small coloums of air trying to straighten out and join together.





     Actually from my learning experiences the small columns will help orientate the air flow unless like you said using too small of a screen , it is even worse of an effect like what your describing that happens with regular air filters, they filter the air but it all gets churned up going thru the filter. That is why honda put the stacks inside the box after the filter, and the true purpose of a velocity stack is to condense the air, if you think about it you take the air space of a large opening in a pipe and force it thru a smaller opening at the other end of the tunnel the air becomes compressed giving you a little more compression in the combustion chamber. These stacks are so small they probably don't have that much of a performance effect there's not much area to scavenge large ammounts of air.  I'm not sure if many people remember the the good ol' monster ram air intakes with 6in tall stacks on top of a monster flat head v-8....... man that's good times

[eldar]

Ok so modify things so there are scoops on each side with the screen at the front about an inch after the opening. It will filter some and then the air can smooth out before going into the filter..

But a person never knows till they try. After all, look at how many things were supposedly impossible and are now everyday things. But I cant tell anyone to not assume things just cause they do not think it will work.