Topic: Indivdual carb air filters? .. Worth it?

[Flying Tiger]

Hi, .. a couple of questions from a novice, for someone who has fit seperate filters on their bike. I've sort of thought the carb box on the CB 650 that I have seems a bit restrictive, .. that true?

Whereas seperate air filters, like the kind offered on Ebay, would be a good thing to install, better breathing and such ...

And would that make it possible to blow out the jets occasionally, without removing the carbs? Assuming a person can lift the sliders (vacuum cylinder if you prefer) out of the way to get at them, (and without damaging them, of course?) .. or is it still too tight to get at the jets?

ooo, .. and the noise, .. is that more? .. I'm not into being heard, ..

Thanks, people ..

Ken

[lifeofthe88@yahoo.]

usually no.have to change jets on carbs.depend on exhaust set up also. gettining the correct air/fuel mixture is a pain.is fer me anyhow.are you good with carbs?

[Flying Tiger]

nope, .. I didn't think about the mixture being affected, .. but, it makes sense, .. This would require a smaller jet, right?

I have the stock pipes on.

[lifeofthe88@yahoo.]

my understandin is with stock pipes and pods you might not have to change jets.tricky sitation but overall found it aint worth it.yep more air with pods so bigger jets.i couldnt figure out what size jets to try.too  bad with my project the factory box wont fit my frame and i managed to damage some carb parts.iam trying to get rid of my project 550 chop.its in the bikes for sell section.

[eldar]

generally if you put on pods of change to a 4 -1 exhaust you will usually have to rejet. Not so much with the exhaust but most certainly a good chance with the pods. You will have to go to LARGER jets not smaller.
Many have been finding out though that pods offer erratic operation and are not as good on low or mid range, only high.
Best bet is to get an UNI filter and keep the stock box or use some kind of box that will equalize air flow.

Some have even had trouble with how they place their knees when using pods.

[hymodyne]

Tons of discussion threads on pods that you can investigate...I started with them on my bike, then went running back to my factory box and a UNI replacment filter element for the consistency they provide in terms of tuning and performance. If you have the time to re-jet and change needle clip settings, go for it.

hym

[dusterdude]

the only problem i have with pods,if it is the correct problem,is at about 65 mph i seem to run lean.i suppose jetting would take care of that,but i may put the stock box back on this winter.not sure yet.

[ProTeal55]

My bike came with velocity stacks in place of the stock airbox. The bike runs fine , so I am guessing the previous owner(s) jetted the bike to match the stacks. I have yet to rip the carbs apart to see if this is true.

I bought a set of pod filters for the bike , and noticed no changes in how the bike performed , from when the velocity stacks were on their..

We will see what happenes when I put a 4 into 1 on the bike in the spring....

[murtceps1]

I have pods fitted and find getting the mixture right a night mare. If pods are not clean  you have one set of problems , and If they are you have to re-jet you carby to compensate for the altered air flow. There are a number of discussions going at the moment on this subject.
If I could go back to std I would in a flash.

[DammitDan]

I have the same problem as dusterdude with my pod filters... Get up past 65mph and the bike starts acting up and chugging/bogging.  Takes it a little while to get back to normal riding at secondary road speeds.  As soon as I get up the nerve to try and cram the standard box back in behind the carbs, I'm going to!

(you may notice that I have pods AND the filter box installed...  stupid rubber box with the boots refused to fit into the space after I connected the carbs to the engine!! grrr...)

[Flying Tiger]

Thanks for all the replys .. Yes, .. I was wrong in thinking about the jetting, .. more air should mean LARGER jets, not smaller ..

The original idea of removing the twists of the stock air flow doesn't seem to be easily solved, by what the comments have been ..

I was speaking to another bike owner about this subject, .. And I mentioned to him that another thing that would be interesting is a narrow scoop (very narrow, because of knee clearance) on each side that would curve in a semi-circle into the carbs. He mentioned that someone has done that for Harleys, in a custom shop, not far from where I live, .. it sounds like a patent is involved, too. But, wow ... Wouldn't it be nice to be able to cram air into the system, in this simple way, assuming you can keep good mixtures, at various speeds. I may stop in at this shop, at some time, and find out more. I'll post anything meaningful, in this thread.

Thanks men, for the comments ..

Ken

[paulages]

the only problem i have with pods,if it is the correct problem,is at about 65 mph i seem to run lean.i suppose jetting would take care of that,but i may put the stock box back on this winter.not sure yet.

i've heard of such problems due to inceased air flow around the outside two carbs at hight speeds. rather than having atmospheric air pulling from a dead(ish) air space in the frame, it is pulling from the air rushing by at high speeds, and the result is that cyl. 1 and 4 run too lean until you slow down. supposedly if you make a little shield on either side it eliminates this.   

personally i like the look of pods, so if you're gonna have something extra on the side of your bike, why not let it be the side covers that cover the stock air box anyway?

[seaweb11]

I think the "air flow problems" with pods is a wifes tale!

I put a 4-2 exhaust on my bike and had to adjust the carbs a bit, and when I put the pods on had to go to a 38 main jet.
It only takes and hour to remove carbs-replace with larger main jet and put them back on.

LOVE THEM and have had no problems with "My knees or leg possition?" Come on now.

[paulages]

I think the "air flow problems" with pods is a wifes tale!

maybe so, but i know that there are many subtleties to engineering that aren't immediately visible nor easily diagnosable.

 props to mr. honda and his engineers!

[TwoTired]

I think the "air flow problems" with pods is a wifes tale!

The wife must be operating above 30-40 MPH.

I put a 4-2 exhaust on my bike and had to adjust the carbs a bit, and when I put the pods on had to go to a 38
 main jet.

Really?  You must get phenomenal gas mileage. Most CB750's operate with #105 to #120 mains.

LOVE THEM and have had no problems with "My knees or leg possition?" Come on now.

Glad you're happy.  Have you compared your inner to outter spark plug insullator colors after a half hour cruise at 70MPH?  Where do your carb fuel vents terminate?

[seaweb11]

TT  "Very touchy today", once again we agree to disagree

Bike runs great at low speeds. "The pumpkin parade is comming up and I can't wait".
Gas milage was not my purpose for building this bike.
Very happy thank you. 4000 mile hwy trip this summer, still no issues you have related to in the past.

[Buffo]

I have never run pods...I have a K$N factory replacment flter in the stock air box and I run a 4 to 1 header only...no pipe...I had to get bigger slows but my mains appear to be fine...

It seems that it would be better for street applications to run some sort of "box" that would allow each carb to draw the same air from a common source...in racing...REAL RACING...things are different for each application and what is good for the goose is not always good for the gander...

unless you are running a engine with MAJOR perfomace upgrades your engine simply does not need that much more air...drilling your stock air box in the proper place would add more than enough air flow for most applications

if you like the looks of a "ram-air" scoop fine but I think that at higher speeds the bike might run mighty lean due to too much air...bikes that need ram-air scoops tend to be drag bikes that are ment to run one way...wide open... and are jetted for that...they tend to idle like crap and forget about slow speeds

DONT GET ME WRONG! I like to hear that some of you guys are tring "new" things...as for me when my bike get a total overhaul I WILL put some long hours in on two upgrades to very modern technology...RADIAL BRAKES...FRONT AND REAR!

Buffo The Magnificent

[TwoTired]

Actually sw11, since you report a phenomenally fantastic pod solution I was hoping you'd share real numbers and data about your total set up.

You may have a #38 slow jet, but this is so unrealisticly small for a main jet, I though I might goad you into a correction to your post.  If you don't want to help out others, then do as you wish.

Aerodynamic effects on a motorcycles exist regardless of whether you observe them or not.  These effects don't come into play until the bike starts moving significant air out of its path.  Surely you've noted a strange pressure on your chest as the speedometer needle winds it's way from the at-rest position toward the upper end of the scale.  Somewhere around 40mph is where the pressure begins to build and this increases with speed, and therefore, volume of air moved.  Also, you might notice that any loose fitting clothing billows away from your body at your back in a general bubble shape.  It forms this bubble because the air near the center of your back is at a lower pressure than that close to your sides.  The air flowing around and behind your engine is subject to the same effects.  The carbs near the center, behind the engine, exist in a lower atmoshpheric pressure than those near the outside of the bike when at speed.
I asked you about the carb vents, because if they were removed, then the carbs can be relatively uneffected by differeneces in jet flow since the atmospheric pressure on the fuel in the bowls would be about the same as that present at the carb inlet inches away, causing the jets to flow properly and leaving the mixture ratio about the same as the outer carbs, even though they may be in a different pressure area than the outer carbs.  Normally, on a stock configured bike, the vent tubes are fed atmospheric pressure from near the bottom of the bike. And, all carb inlets are fed from one source tube.  With pods, the inner carbs can see different inlet pressures (at the bikes higher speeds) relative to the carb bowl vents, and this can cause the inner carbs jets to flow at a different rate than the outer carbs.

Since you don't care about gas mileage, the inner vs outer carb mixture differences can be partially masked by running the bike in all the upper throttle settings over rich.  But, there might still be differences in plug readings after a long cruise at speed.  Something I though you might share.

If you don't wish to share the data details about your fantastic miracle set up, you are certainly free to express your opinion that you love pods for whatever reason you wish.

Please keep the rubber side down and enjoy your bike.
Peace,

[paulages]

yeah, that's what i was trying to say...ouch!

[amattel]

I have my own pods story.    cb750k2 has the WISECO 836 kit installed with 4-1 exhaust, cv carbs from an '82 cb650sc, and pod filters.   I do not know the details of my jetting as my mechanic set it up similar to his drag cb750 whcih also used the 31mm keiun(sp?) carbs from the cb650sc he installed for me.  I was so excited to get hte bike back after being without it fro 3 months while he rebuilt it for me that I didn't ask all the questions I ought to have asked.  When I get bac k to arizona I will get the details from him.

with my fairing installed I found that if the wind was blowing from my left and I was travelling over 60 mph or so, I would lose power erratically.  In this condition, the the situation was directly affected by moving my knees away from the bike... I would instantly get power back by doing this...

Recently I ditched my fairing and have fell in love with the bike all over again.  I wouldn't have thought taking off a piece of plastic would make such a difference, but it is like a totally different bike in how is rides.

with the fairing removed the pods work quite diferently for me...  if it is windy, I often lose power, however there is no association with a particular wind direction...  and moving my legs, though it still helps, doesn't help as much as it did before.

I am considering fashioning some sort of shield for the two outer carbs.  I have been watching ebay for a custom air box that would fit, but I have been outbid everytime so far.  The newer carbs are longer so the stock air box won't fit.

has anyone actually tried putting shields on the outer carbs?  I am hesitant to put forth the effort if it isn't actually going to help.

that my story and I'm stickin' to it! *smile*

Adam

cb836k2

[jurob]

fabbing a shield should be quite easy. in the 5.0 mustang craze, a heat shield is used regularly for cone filters mounted in the engine bay to block heat and engine wash.

im gonna experiment with pod filters because i hate reinstalling the stock airbox. if i run into trouble i will fab a shield to run on both sides.

[seaweb11]

TT......WOW from me as well! 

1st,  I don't own 25 Motorcycles, and I am not a doctor!   Far be it for me to tell you anything beyond my experiences. I was just saying it like it is for me.

When I put on the pods...it ran like #$%*! I knew it would need re-jetting and adjusting so... I have a mechanic at the dealership near me who enjoys old bikes and he did the initial work. He put in (136) main jets "all he had" and he set it up as best he could. He indicated I would need to go a bit bigger so I did the (138) install. I just assumed most would realize I meant 138 when I typed (38) in my earlier post

The air vents you refer to are as stock, the tubes still drop in their normal position down low. I'm sorry it runs so great. I have no idea why?
It goes like snot!

I have no issues with low (under 2000-3000 rpms) I have no issues with high speed engine poo.
I get no back fire under de-acceleration, rain has not been a problem either. My pant leg has never interfered with the pods, the wind has never effected the rpms or speed or sound or

I don't have a degree in Hondas, I don't profess to "know it all". But I did figure out how to put pods on my bike and it turned out great! I don't ride on dirt roads, so dust doesn't seem to be a problem.  I take them off every month or so and spray them with Filter cleaner, rinse them off, let them dry and put them back on.

I have read just about every Pod thread on this post since I joined. That is how I kind of had an idea of how to do it. I have read where others have had success as well.

When people have asked the “pod” question I answered with my experience which has been positive.

With all these bikes you have listed, have you never tried?
Sometimes if you don’t know it won’t work it can:-)

EVERYONE!    MINE WORKS GREAT!

P.S. I am now done and will not be confusing anyone further, please refer all other pod enquiries to ( I’m Too Tired )
It can’t be done,  it won’t work,  don’t even try.

[TwoTired]

TT......WOW from me as well! 

I never said that pods couldn't be made to work.  In fact, I've said that they can, but it takes knowledge and proper adjustment of the carbs.  It's not easy unless you understand what the carbs need to work properly, as you already learned.

I've had pods on two Cb550s.  One was Uni foam type, the other came to me with the folded paper type.  The one with the Unis I eventually got to run okay with some carb fiddling.  But, in the rain, the foam clogged up and then the bike fouled plugs on 1&4; the outer cylinders.  I eventually swapped back to the original air box set up with a Uni foam filter, undid most of the carb adjustments, and it became a reliable wet and dry weather machine.  I didn't notice much power difference between pods and the stock airbox.  But, I didn't dyno the machine or do timed speed runs either.
The other 550 with pods has other problems besides the carbs.  I haven't decided yet whether to spend time on the carb adjustments or just restore the stock airbox; project in waiting.

Thanks for providing more details on your set up.  Perhaps others will make good use of it.

Sorry, if you felt I was attacking you.  I had some tooth pain and a root canal pending and I suppose I let some of that discomfort bleed into my postings.

Best of luck,

[amattel]

Jurob

fabbing a shield should be quite easy. in the 5.0 mustang craze, a heat shield is used regularly for cone filters mounted in the engine bay to block heat and engine wash.

im gonna experiment with pod filters because i hate reinstalling the stock airbox. if i run into trouble i will fab a shield to run on both sides.

I wonder how much of a shield would be necessary...  I can visualize a curved piece, perhaps half an inch from the filter curving around it.. perhaps 120 degrees (1/3 around).. extending 1/2 inch beyond the end of the pod...

could be attached by the same metal band the holds the pod on...

Would this be enough of a shield?

//what would one make this from?  Sheet metal?

I am inexperienced at this "fabbing" thing.

Has anyone seen or heard of this being done on a bike with pods?

Adam

[paulages]

i've heard of this being done, and if you search the greenspun archives, i bet you'll come up with an answer.