Topic: Pod Mod - It actually works...

[crystalhelix]

So...I was getting overly frustrated with having to heatgun my stock airbox and I wanted to go to pods anyways.  Well the damn things make the carbs go haywire on my bike anything over 45 mph due to the way the air moves over the bike and causes some kind of pressure center in the area where the stock air box used to be which probably makes the carbs lean out (guessing, no proof) and the bike fell flat on it's face. 

I have rejetted to 120 mains with the needle clip one off the bottom (1 setting richer than stock), stock 40 primaries.

So I got to thinking about the issue and was going to build an elaborate box over the cones so they would be out of the draft at speed.  Essentially like an airbox...which got me thinking.

Why not keep the carbs out of the wind from the inside, and on top of that why not make the carbs think they have something more like the stock airbox strapped to them.  Oooo...I had an idea.  So I measured the stock airbox inlet (see sig for bike info) and it's about 2.4 square inches if I remember correctly.  So I decided I need to somehow give each of the pods a 2.4 cross section while keeping the drafy air away from them.  So I got myself some aluminum (0.025 sheet from Lowes) and started futzing...

I got a piece of paper and wraped it around the filter to make a pattern (which had to change cause I realized it was pretty much only good to mimic the outside of the filter).  And I was going to figure out a way to put in on the pod.



Then I thought to myself why not save the look of the pods and put the baffle in the pod. 

Crap, I have to trim the original down and get it to fit inside.  This took some time.

4 baffles


Then to fit them to the inside and get the opening size I wanted.  The pods I have are EMGO and they are about 2 inches long.  Take an averate of these dimensions and you get around 2.25 inches but I figured they wouldn't have the pressure drop the stock airbox has so I went a tiny bit smaller with the gap.  The point is you can make the openeing whatever size you want as long as it works to baffle the cone from sidewinds etc...ie you want to have at least half of the outside cones (1 and 4 cylinders) covered to keep the wind out.

I think these are pretty close to what I got but for some reason I am thinking I should measure the numbers again, but you get the point of the idea right!


So now theoretically I have supplanted 4 mini airboxes on the bike.  Now onto that whole pressure theory, I wanted to get the the filters protected from side draft so I oriented them like this.

copied and pasted for simplicity sake..


This profides a baffle to both out side carbs from the wind.  The reasoning for facing the inner carbs to the outer carbs is purely so they would both be drawing air from the same place on the bike and hopefully this would make all four cylinders and carbs have better balance and run more smoothly.

One suggestion is to make sure the curvature you put on the baffle presses it firmly against the inner surface of the filter so it cannot become loose and start rattling around in there, or rotating, for the final install clean up any burs that make become loose, you don't want that stuff going in your engine.  Also, don't try this to make a small baffle or basically any baffle that's going to get sucked into those beautiful carbs we all love (and hate.)  (insert disclaimer here that I am not responsible for ruining your bike as I am just a guy on the internet typing my ideas )

I threw everything back together and decided I would try out this crazy idea.  Damn if it didn't work for me.  I went out and cracked that thing up to about 90 miles an hour and then ran into traffic.  Things aren't perfect but it seemed to solve a lot of my problems.  Now if my F only had an accelerator pump...

Enjoy and feel free to ask questions..

[kslrr]

Interesting idea.  That is the same problem I was experiencing on my 350F when I put pods on it.  It would run great until the engine warmed up.  I figured that carbs 2 and 3 were getting hot air off the engine.  So now I am working on a fresh air intake system using plastic drain traps.

cut two pairs of traps at an angle (carbs 1 & 2, carbs 3 & 4)

glue together

mount to two carbs

[seaweb11]

"Well the damn things make the carbs go haywire on my bike anything over 45 mph due to the way the air moves over the bike and causes some kind of pressure center"

Do I have a bike from outer space...perhaps from a different reality plane

Every time I read a post on "the wind screws up my bike with the pods" I go outside and look at my bike and say quietly to her "it's  OK" "We are different you and I"  we live on a small planet called...................Wonderland

MY BIKE RUNS GREAT WITH PODS< EVEN LEANING INTO A 25 mpr side wind in Eastern OR on the way home from SF.
3 years since I put her together and no issues

It is a K8 though

[pddpimp]

I had the same pod problem. I found that it matters where your legs are while riding. Im a large guy for one of these bike (6'5", 230lbs) and I find that the air deflects off of my legs and right into the outer pods. Which in turn leans them out pretty good. I moved back on the bike, to act as if my legs were shorter, and it ran better. If I didn't hug the tank with my knees, it would really run like crap. These tests were done at freeway speeds. I have since switched back to a stock air box.

Just my 2 cents, from this small far out planet I call earth.

People with K8s are super lucky I guess

[Terry in Australia]

The reason your bikes act up with pods is that they are running lean, and that "mod" is just adding a "choke effect", causing it to run richer. Like sticking your hand over the carb's bell mouth.

The reason Derek's bike runs fine with pods is because it has accellerator pumps that richen the mixture by squirting a shot of raw fuel into the combustion chambers when he gives it a handfull.

It's still running too lean though, and wearing the engine out at an accellerated rate. Cheers, Terry.

[seaweb11]

It has been re-jetted properly and I'm comfortable with it.   I'm going to run it into the ground with a smile

I have a spare

[Terry in Australia]

You'll need it................ 

[crystalhelix]

I like the poster with the plumbing traps on his bike, some bondo and paint and that should work, lol.

I posted that I have made jet changes in an effort to show I am not trying to run stock but that this helped solve my issues.  I feel I can finally start doing some plug chops, etc.. to start fine tuning.

Thanks for the feedback and I just wanted to start a topic for those of use looking for solutions to our carb issues.

[TwoTired]

The stock air box goes on and off rather easy for the 750 with soft, new couplers.

If you calculate the inlet area of your pod mod.  I think you will find it far less than the stock filter area.  Area loss won't be a significant performance factor at idle air speeds, though it will increase throat vacuum and it's ability to draw from fuel jets.  But, it WILL make a dramatic performance effect at 8000 RPM.  Like operating with the choke on.

If you don't want to play with Main, idle, and jet needle fuel metering, simply buy new air box rubbers.  (Free advice!  You know what that's worth.)


Cheers,

[crystalhelix]

The stock air box goes on and off rather easy for the 750 with soft, new couplers.

If you calculate the inlet area of your pod mod.  I think you will find it far less than the stock filter area.  Area loss won't be a significant performance factor at idle air speeds, though it will increase throat vacuum and it's ability to draw from fuel jets.  But, it WILL make a dramatic performance effect at 8000 RPM.  Like operating with the choke on.

If you don't want to play with Main, idle, and jet needle fuel metering, simply buy new air box rubbers.  (Free advice!  You know what that's worth.)


Cheers,

TT - I understand what your are saying but I was basing the area on the opening that the stock airbox has underneath it.  I like the cones for now.  If at somepoint I can stop working on the bike and I will consider going back to stock but for now I have to concentrate on fixing the rear brake cylinder, lol.

[kslrr]

I like the poster with the plumbing traps on his bike, some bondo and paint and that should work, lol.

How much bondo do you think I will need?   , and what color should I make it?

[750essess]

120 mains are too lean for a 750 with pods, Should be 125's at least. Then you can take out your restrictors.

[edbikerii]

Wouldn't it be easier to just re-jet properly?   What's this irrational fear of changing out jets, turning idle mixture screws and raising/lowering needles.  Once you've done it once, it is pretty easy.  The worst part is waiting for the jets via UPS.

[TwoTired]

The stock air box goes on and off rather easy for the 750 with soft, new couplers.

If you calculate the inlet area of your pod mod.  I think you will find it far less than the stock filter area.  Area loss won't be a significant performance factor at idle air speeds, though it will increase throat vacuum and it's ability to draw from fuel jets.  But, it WILL make a dramatic performance effect at 8000 RPM.  Like operating with the choke on.

If you don't want to play with Main, idle, and jet needle fuel metering, simply buy new air box rubbers.  (Free advice!  You know what that's worth.)


Cheers,

TT - I understand what your are saying but I was basing the area on the opening that the stock airbox has underneath it.

I think you missed the point.  The stock filter area is much larger than the inlet of the air box.  This is because the filter media has tiny holes and you need a lot of them to to approach the inlet cross section area.  You have not only restricted the inlet, you have reduced the usable filter media area also, and, therefore, restricted the inlet area far more then the stock air box inlet.   If you get fouled plugs out on the open highway, you now know why.

Cheers,

[crystalhelix]

The stock air box goes on and off rather easy for the 750 with soft, new couplers.

If you calculate the inlet area of your pod mod.  I think you will find it far less than the stock filter area.  Area loss won't be a significant performance factor at idle air speeds, though it will increase throat vacuum and it's ability to draw from fuel jets.  But, it WILL make a dramatic performance effect at 8000 RPM.  Like operating with the choke on.

If you don't want to play with Main, idle, and jet needle fuel metering, simply buy new air box rubbers.  (Free advice!  You know what that's worth.)


Cheers,

TT - I understand what your are saying but I was basing the area on the opening that the stock airbox has underneath it.

I think you missed the point.  The stock filter area is much larger than the inlet of the air box.  This is because the filter media has tiny holes and you need a lot of them to to approach the inlet cross section area.  You have not only restricted the inlet, you have reduced the usable filter media area also, and, therefore, restricted the inlet area far more then the stock air box inlet.   If you get fouled plugs out on the open highway, you now know why.

Cheers,

I get what your saying but I guess I don't go driving around in dust storms and with the open areas facing inwards I can always just move the baffles to a clean section and rotate the pods.  It's hard to match the all around performance of the stock airbox, I have no qualms with you about that argument.  But I am willing to make at sacrifice until I can get it dialed in.

[crystalhelix]

Wouldn't it be easier to just re-jet properly?   What's this irrational fear of changing out jets, turning idle mixture screws and raising/lowering needles.  Once you've done it once, it is pretty easy.  The worst part is waiting for the jets via UPS.

I did reject and re-needle locate - I still had problems with air blowing over the cones at speed.  I am 5'9'" and 230, when I move my legs to diffent positions the bike actually performed differently while riding at >40mph..

[bikerbart]

Hey man,check out my thread.Pod filters cheap fix.I do not have pics because the stupid pc is fighting me,but,I stand by what I did because my bike runs better now than it ever has.stock motor,4-1 header,emgo pods(cheap)110 mains,7 ounce bean cans(or tomato etc.)over the pods with about 1/2 inch of actual filter element showing,and it runs great at most if not all rpms in all sorts of riding conditions.sweet spot 60-85 mph purrs like a kitten,no more like roars.AND,I get over 100 mph with more to go.73 cb750 23k.

[MCRider]

Wouldn't it be easier to just re-jet properly?   What's this irrational fear of changing out jets, turning idle mixture screws and raising/lowering needles.  Once you've done it once, it is pretty easy.  The worst part is waiting for the jets via UPS.

I did reject and re-needle locate - I still had problems with air blowing over the cones at speed.  I am 5'9'" and 230, when I move my legs to diffent positions the bike actually performed differently while riding at >40mph..

I always ran Pods as I like them eaesthetically, but incurred crosswind performance problems, and said so what.

But we should rememeber the full engineering name is not "air box" but "still air box". Meaning the original air box was designed to store air long enough that it could settle down before being sucked into the carbs. Thus easier to jet and not susceptible to crosswinds. The problems of 4 carbs in a row were anticipated. 

[coyotecowboy]

120 mains are too lean for a 750 with pods, Should be 125's at least...

125's and fourth position on the needle here, and I think I should probably go up to 127's or 130's.  Still feels a little lean at highway speeds.  Anyone have experience with 127's or 130's on a 750?

[seaweb11]

WHAT BIKE?

[joe_and_jeep]

I gotta get pics of mine.  I run 4 tennis balls 

[coyotecowboy]

WHAT BIKE?

duh!  K2 750, foam pods and 4 into 1 with most of the baffle removed

[BobbyR]

It boggles my mind that people go to great lengths to re engineer what has already been engineered. I am sure the Honda folks did wind tunnel testing to study airflow around the bike and position the air intake in the proper spot for good overall performance. Yes, ignition systems can be upgraded with newer technology, tires have been improved, progressive springs and better shocks. Those are the things to focus on. Pods are cute, but fairly useless.

[seaweb11]

It boggles my mind that people go to great lengths to re engineer what has already been engineered. I am sure the Honda folks did wind tunnel testing to study airflow around the bike and position the air intake in the proper spot for good overall performance. Yes, ignition systems can be upgraded with newer technology, tires have been improved, progressive springs and better shocks. Those are the things to focus on. Pods are cute, but fairly useless.

Unless they work fine from the get go   Never had an issue with mine

[Terry in Australia]

That's because you're running carbs with accelerator pumps Derek, that fire a squirt of raw fuel straight into your inlets every time you tug on the throttle. You won't notice any problems until you burn out an exhaust valve. Cheers, Terry.