Velocity stacks VS K&N Filter

[Samuraiace]

I've been looking into getting velocity stacks and was wondering what was the best to run weather it was replacing the K&N filters I have or picking up the velocity stacks?

I've heard you do get a minimal extra power boost from the stacks, Is this right?

I'm trying to figure out some of the Pros & Cons of both and then weigh the difference to get my answer, so any help in this department would be very appreciated.

Thanks

 

[TeeCat]

Samuraiace -

Stacks have the net result of creating a venturi effect that delivers a great deal more air to/through the carb, hence leaning the fuel-to-air mix significantly, often enough to cause performance problems if the carb(s) is/are not re-jetted to compensate. Moreover, stacks are not really designed for street applications (though they can be used as such), and only filter as well as the foam and/or screen that is installed in the stack.

My own experience with a stack, which I had installed to overcome a space limitation, was such that it caused an off-idle lean stumble. The installation of an oval K&N filter immediately corrected the problem.

So, you can use stacks, but your jetting across all the circuits will have to accommodate the air that they are capable of introducing to the fuel delivery equation.

TC

 

[Ironsled77]

Yup what TC said. I would suggest filters. Stacks aren't for street use. I don't think it is worth the headache

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[Samuraiace]

Hey Thanks alot guys Sounds like I got my answer

Any filters you guys find that fit/work the best ?

 

[TeeCat]

Well, K&Ns are quality and highly recommended. Can't go wrong with them, though they tend to be a little pricey. And it depends on your carb type and the outer diameter of the bell/mouth. I am using a Mike's XS oval as a tester on my VM36, and it seems to be just fine. But whatever you use, make sure it has NO STEP on the mounting collar so you don't block any ports on your carb bell/mouth.

TC

 

[Samuraiace]

Alright will do TeeCat

Mine came with the K&N filters when I bought the bike but it seems like they keep slipping off my bs34's, plus there condition now is a bit on the shabby side.

I'm really diggin your tins, are they personally made or ordered from somewhere?
either way there really sick

 

[Pierrax]

Are we sure K&N filter give more power ? Any measurements ?
And what about using foam filters like RAMAIR for example ?

 

[TeeCat]

ace, replacing them is cheap insurance then... sounds like it's time for new ones. Just get the right size for the carb mouth.

By tins, you mean the side covers and/or tank? They're original to the bike, with the original paint. I carefully modded the left cover to accommodate the new air induction. I made the filter shroud, though. Thanks.

Pierrax, the only measurements I have on this are the seat of my pants. Foam filters get wide use on dirt bikes, so I suppose they'd work here if all other variables are correct... jetting, etc..

TC

 

[Stone Hands]

I have a 72 XS2. I took off the stock air box's, added K&N filter pods but went with a pair of heavy duty carb holders for the support, and added a 3/4 inch billet alum spacer/stack to move the filters back just enough to all fit under the original side covers. Looks great and works even better. Had to play with the neddle a little to get it balanced however.

 

[Samuraiace]

I had a previous thread about a set of velocity stacks I was thinking of purchasing and someone had wrote about using a set with foam inserts behind the wire mesh.
If I did something like that would my carbs need re-jetting?

 

[Samuraiace]

Just found out that the P.O before me put the filters on and didn't rejet the carbs.

There stock 80 special II bs34's, any thoughts on what I should rejet them too?

 

[5twins]

You'll probably need one up on the pilots and one or two up on the mains. I highly recommend the UNI foam pods. Cheaper than K&Ns and easier to tune for. Honestly, I consider most cheap pods, even the ones from Mikes, just a waste of money. There are some areas on a bike you can cheap out on and save money (cheap chain, paint it with a brush). The air filter isn't one of them.

 

[Samuraiace]

I know alot of people are on a tight budget when building up there XS (self included ), but I got to agree when it comes to filters, and engine parts I don't scrimp.

5twins- can I go straight to two up on my mains with the uni-pods, or is there a lot of difference between one and two up?

 

[Samuraiace]

Should I upgrade the needle to a clip style one or stick with what I got?

 

[54inches]

I have a 72 XS2. I took off the stock air box's, added K&N filter pods but went with a pair of heavy duty carb holders for the support, and added a 3/4 inch billet alum spacer/stack to move the filters back just enough to all fit under the original side covers. Looks great and works even better. Had to play with the neddle a little to get it balanced however.

Do you have pictures?

 

[5twins]

If you have pods and a pipe change, I would start right at 2 up on the mains. If you install the adjustable Canadian needle and matching needle jet (much richer than stock), you may not need a larger main but I would try at least one up just to make sure. Personally, I don't think the Canadian parts are needed most of the time. You can usually tune the 34s well enough by just changing mains and pilots. And for less money, too.

 

[Samuraiace]

Alright sounds like a really good place to start thanks for the info 5twins

 

[Ksboy19]

I heard somewhere that if youre going to run airfilters you need to have baffles because it will throw off your fuel to air mixture or something like that. Is there any truth to this? Or maybe youve heard something different. I wasnt planning on using baffles unless I absolutely had to.