• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

Filters VS Velocity Stacks.

  • Thread starter Thread starter TheCafeKid
  • Start date Start date
T

TheCafeKid

Guest
Have an oppertunity to purchase some velocity stacks for VMs. Looking for some info. Im not familiar with them other than i think they LOOK sweet..lol These would be going on my 77 750B cafe build.

What are the differences in jetting for them vs pod filters? Seems the would let more air in correct? Secondly, what advantages are there to using them? Disadvantages?

Thanks for any info :)
 
The advantages are mostly for racing. With less restriction and a shape that smooths the incoming airflow, they allow the most air possible.

The main disadvantage, as I see it, is no filtration of incoming air. They still smooth the incoming flow, but at lower rpm (road speeds), it is not as important as it is at higer rpm (race speeds). They will, of course, be noisier than a stock airbox, but I don't think they would be any noisier than pods.

I have no idea about jetting differences, but I would guess that they might need a slight increase in jetting.


.
 
These particular happen to have the screens over them, for sure not as effective as foam filters or the mesh action of the EMGOs but it has to be better than nothing eh?
 
the stacks straighten the air and speed it up.
the jetting difference is very minimal just a size or two difference- maybe

when you get a gas engine running good the window is 10% on main jets

too lean to too rich 10% is what I mean on the main jets.

the trick is to find the edge say it cracks up with 107.5 but pulls clean with 110 on the lean side. then the rich side will be approx 121

this is an art because the atmosphere and humidity don't always behave. but finding the edge will get you in a good position to tune for the minute difference in stacks and filters.

pilot is easy to adjust and needle will come after you get the right main.
 
filtering the air is overrated if you don't mind honeing and reringing the engine once in a while. unlike a calm, pampered street engine where the rings have never seen the light of day. ugh!
 
Well as per Keith's suggestions, ive gone to a 127.5 main on my particular set up, stuck with the 17.5 bleeder, (8v 750, pods, V&H 4into1, Dyna S, no bore/cam mods) with my needle at the 4th position down from top. Will this be too lean or should i be able to dial it in with this set up, vs the pods? I know this is tough to really answer, just looking for opinions.
 
I run 'stacks on my CB450 because they look cool.

I know they're bad for the motor - after I blew it up the one remaining piston looked sandblasted afer only 100 miles :(

But I'll leave them on because I'd still rather look cool. I have other bikes if I want to ride something that won't wear out quickly.
 
Well thats no good..lmao Im not entirely sure i want to destroy my motor for the sake of looking cool..be different if i had another bike handy, but not as of yet. I was more concerned of what sort of headaches i was getting into in trying to jet with them. Perhaps i will stick with the pods.
 
put them stacks on and begin tunning again. do the choke test on the highway and your bike will "tell you" what to do- richen me up or leave it be.

the pods do not filter very well even if you oil and clean them weekly
 
Last edited:
TheCafeKid said:
Well thats no good..lmao Im not entirely sure i want to destroy my motor for the sake of looking cool..be different if i had another bike handy, but not as of yet. I was more concerned of what sort of headaches i was getting into in trying to jet with them. Perhaps i will stick with the pods.
Click to expand...

Stick with pods.

My CB450 is a cafe racer designed for cafe racer bar nights, scooter/cafe racer rallies, stoplight drags with other vintage bikes & scooters, errands in hip neighborhoods and general posing. It's loud, moderately fast and looks freakin' cool. But it's not designed to go too far or stay together very long.
 
Tripp, not familiar with a highway choke test. Plug chops and what not sure, but never been down that road. Enlighten me please?
 
TheCafeKid said:
Tripp, not familiar with a highway choke test. Plug chops and what not sure, but never been down that road. Enlighten me please?
Click to expand...

When you're flogging it down the highway on the main jet, pull the choke out a tiny bit. If you go faster, your jets are too lean. If it slows down, too rich.
 
But only in the main and needle setting right? or all thru the system?
 
TheCafeKid said:
Have an oppertunity to purchase some velocity stacks for VMs. Looking for some info. Im not familiar with them other than i think they LOOK sweet..lol These would be going on my 77 750B cafe build.

What are the differences in jetting for them vs pod filters? Seems the would let more air in correct? Secondly, what advantages are there to using them? Disadvantages?

Thanks for any info :)
Click to expand...

They do look cool. I'd like to find a set for my project.

What Steve said on the pros and cons. I would think the jetting should be close to what you would have if you used K&N's. Maybe one step richer, or maybe just a raise in the needle would be all you would need.

Are these velocity stacks new? I've been searching.
 
I just may. Im also looking for a good set of K&N pods, more faith in those.
 
Velocity stacks won't harm your motor.....just as pods are less effective at filtration than the factory airbox.....the stacks are less effective than the pods....if it were you daily driver....then maybe no....is it going to be the REASON you have to rebuild or rings.....not likely....will it take a few thousand miles off your rings life? Probably. I've always loved the look of velocity stacks....Hell....that's half the reason I bucked up the big $$ and put a four weber setup on my 66 Mustang.....
 
robertob said:
When you're flogging it down the highway on the main jet, pull the choke out a tiny bit. If you go faster, your jets are too lean. If it slows down, too rich.
Click to expand...



yep that is the choke test. it works everywhere when you are lost in solving a rideability problem involving fuel control.

the bike should NEED choke on normal cold start up.
pilot- the choke should kill the bike if it is hot
mid range- the choke helps until too rich
main- the choke should not improve power at W.O.T.

at least you get an idea where the bike's jetting is at. how far to change is up to you.
 
Unless you're riding in a desert you should be ok - my mate's old BSA A10 has done 65k (at least) on bellmouths (UK equivalent of velocity stacks). The old girl's still on standard bore and probably will be for ever.

There's a lot of maths in bellmouth design - don't ask me - all I know it's to do with creating the holding area for the fuel / air mix that got 'bounced back' when the valves shut on the previous stroke. What I do know is that they can be very susceptible to crosswinds on tickover (+ or - a lot of revs).

If they're a well designed set they've got to be worth a go I'd say.
 
You must log in or register to reply here.
Back
Top