Pod Air Filters

Just received some in the mail. before I install, what else needs to happen?
I need to remove the plastic box under the seat, which everything is mounted to. (battery,various electrical) I guess my big question in the engine's air cooling exhaust also feeds into the same filter box under the seat.

what do I do with said hose? does it need a filter, can it just breath free?

 

the subject is POD AIR FILTERS BTW, I thought it would be more clear in the forum.... (I'm new to this)

 

Well, you will need some carb re-jetting for sure. I used dynojet's stage 3 kit for my pods.

 

Put the model of your motorcycle(s) in your signature, so we know what you are talking about.

The hose you are talking about is from your crankcase (engine, not exhaust). It is a breather hose that feed oil fumes that exit your crankcase when it becomes pressurized into the intake, where they can be combusted rather than released into the environment. You will need to put a filter on that spigot, or you will be allowing the environment to contaminate your oil.

But as far as I know, nothing is actually connected to an airbox except the fusebox. You don't actually remove the airbox from the side of the frame (although pulling the battery box and TCI/RR mount will give you more clearance). Depending on the model, you will likely need to remove the engine to get the airbox out cleanly. And you will want to remove if cleanly for the following reason:

Is your bike running PERFECTLY as is? If not, you will likely have issues tuning for pods. If you are set on them, the best advice that I've seen is get it running and tuned properly BEFORE you make the switch to pods, so that you are troubleshooting the pods and not some other condition (valve out-of-spec, carb dirty or in need of rebuild, vacuum leaks, etc). Search this forum for pods, there is much discussion on this topic.

But keep the airbox whole, so that if you have problems tuning for pods, you can always go back.

 

And remember you may OR may not be able to get the bike to run right with the pods. It may take a lot of adjusting to get them to work on your bike. You may never get them to work with your bike. Some people have, some have not. It wont be something you are finished with in a few hours. It may take days even weeks or maybe never to get it to run right. These bikes are not designed to work with pods. So do not destroy or get rid of the air box parts, boots etc. You will need lots of patience to do it. I suggest you read the other post by members who have done this before you jump into it.

 

I saw in a thread somewhere that you can heat the airbox up with a heat gun until the plastic gets soft enough that you can "fold" the box in on itself. Then pull it out and return it to it's original shape.

Good luck with the pods.. they sure look cool but like the others said, they can wreak havoc on some machines. StreetBrawler750 suggests that if you use the factory air-to-box boots as a sort of "velocity stack" it can eliminate some of the tuning issues. Here's the thread:

http://www.xjbikes.com/Forums/download/id=8400.html

Let us know how it goes for ya'.. I'd like to do the pods eventually myself.

 

If you're planning to go with pods for an increase in performance-my suggestion is don't do it. Even if you can get the bike to run right with the pods, the increase in power is minor at best. I for one have tried for years & found it nothing but a constant struggle, although I am far from a master mechanic. The best part is I now have a small fortune in various jets sitting around & I think I could remove/install the carbs blindfolded.

Dont get me wrong, I like the idea of pods, they look pretty cool & I wish I have had better luck with them. But this winter Im pulling my motor for a top-end job & will be re-installing the stock airbox.

If you do go with the pods & have success, keep us posted here on how you did it. Everybody here is always open to new ideas. Best of luck to ya.

 

If you have a Seca (sport bike), stay with the original setup unless your going with racing carbs.
If you have a Maxim (cruiser)and want to do pods and exhaust mods, you probably won't miss the high end performance loss that everyone's talking about.
CV carb's don't like pods, you will be doing a lot of tuning. The velocity stacked pod is the simplest way to go. I saw a bike 2days ago that used radiator hoses for velocity stacked pods.
Running pods is possible, but will require some time to get it right.
There was a post about airbox removal the easy way.
http://www.xjbikes.com/Forums/viewtopic ... tml#343222

 

Hate to chime in and ruin the pod party, but the primary reason they don't work is the differences in the air flow and the tiny tolerances built into the small CV carbs.

The airbox unifies the flow and allows almost a perfectly similar charge of air is delivered to each carb. The pods will have restricted (yes restricted) flow to #2 & #3 relative to #1 & #4. The bike needs the same conditions for all four cylinders to run right, this is the problem. I don't know if anyone has tried this but two large pods with a Y-manifold feeding each pair of cylinders would be more likely to tune out right. I agree that the improvement in power is minimal because the stock arrangement is really not restrictive at all in the first place. Of course the pods do look cool, but to really improve flow you would need something like the ram air system the V-max uses.

 

thanks for all the info and insight,
I am on:

1982 xj650

What causes the difficulty in performance of the carbs?
in theory it's just the engine breathing in.
Is it the fact that it will be taking in fresh (cold) air
and not the hot air breathed back out by the engine back into the box?

 

Your CV carbs is a carefully enginered fuel metering device, any change to the airflow will effect the fuel mixture. Giving the engine/carbs more air does not mean it will get more fuel, the fact is it will get less fuel. The CV carb is designed to have the slight restriction of the airbox to have the correct air/fuel mixture.
You can re-jet the carbs to compensate but it is a trial and error process. Each bike is different so the jetting for one may not work on another.

 

-reread posts above
-yes engine breathes 'in'; there is no 'out' to intake unless your valves are not seating
-No

Please don't think you are being discouraged, the response is based on personal experiences with these 4 CV carb bikes (all of them) and how they respond to pod filters and how hard it always is to get them to respond the right way. But it's been done, it can be done, so if you choose to fight the good fight...Go for it.

 

Alright enough of the harping on pods..............Your bike can run just fine if not better with pods. Nobody every has any good to say because they probably didn't take the time to clean the heck out of their carbs or spend the money to try differnt combinations. So tired of seeing guys talk about crap they don't know anything about.

Below is the post I made once I had my carbs dialed in. My bike is fast, responsive and doesn't have a hint of bog or lag. I have an R6 which is obviously faster but the XJ is not far off.



Posted: Tue Jun 12, 2012 10:17 pm Post subject: Re: Spark + fuel = No start

--------------------------------------------------------------------------------

Ok so my bike is officially running and running well!! Did my research and followed the advice of a few. Rebuilt my carbs, Polished the inside sleeves of my carbs, cleaned the heck out of them, new mixture screws, springs, o-rings and washers. I also replaced all of the o-rings on the supply line.

Since I am running a Mac 4-2 and pods, which apparently can't be done well or without having poor throttle response. I swapped my 120 main fuel to a 122.... the stock 43 pilot fuel to a 45.

After reading all the posts I could handle I still could not find out what changes were required for my air jets. I bumped the stock 80 to a 90 and the 195 to a 215.

Then......I wet set and bench synced.

Prior to all of this i checked the valve clearances which were all good. The only thing I had to do was put in heli coils for the valve cover bolts

Fired up first try and idles like a dream.

Hope this helps someone else.

 

Here is the link to the rest of the topic.

http://www.xjbikes.com/Your_Account.html

 

Nothing good to say??

Talk about crap they don't know anything about??

Be honest your experience is great, but do you really think MOST people who make the switch get it right? And exactly how do you know that your bike is "running better" with pods. Did you dyno test it? Are you aware that your R6 is similar to the XJ's only in engine layout?? I-4 that is. Your carbs, compression ratio, wind profile, electronics, ignition, and many other things are quite different.

I agree.

 

gazvanalan...See what you started :roll: . Happens every time someone new mentions pods...

I personally have not tried to tune with pods, although I did have to experiment with rejetting for a free-flowing exhaust. But I will say this:

If you are new to working on inline-4 carb japanese bikes, get it running right, first, with the airbox in. THEN and only THEN should you undertake the challenge of pods. This way, any loss in performance will be due to tuning and not troubleshooting neglected maintenance.

How the air flows through the carbs affects how much fuel gets picked up. The main and pilot circuits are actually separate AIR circuits, which pick up fuel (at a very rich mixture) then mix it with the flow in the venturi of the carb (which results in a combustible mixture). Increasing the air in the venturi does not necessarily increase the fuel being picked up in the other circuit LINEARLY.

Air coming out of the crankcase has oil particles suspended in it. If you release that into the environment, it contributes to pollution. It's really not enough to affect the mixture, but feeding it back into the carbs and combusting it in the engine reduces the pollution (CO, CO2, and H2O vs oil). The actual heating of the air going into the cylinders occurs within the engine itself, and the carb throat. The carbs get heated by the engine when it's up to temperature.

Everything on these motorcycles, like many automotive applications, is an exercise in tradeoffs. You want decent, predictable performance across the entire engines operating range. You also want fuel economy, low emissions. Yamaha's engineers made those tradeoffs using engineering design and TESTING. Can the design be improved, yes, but it's not as easy as just reducing air flow restriction. It's not "hard" to get more power out of an engine, but it means you have to trade other things, even longevitity. Race engines get rebuilt every couple thousand miles...but I'm sure you don't want that undertaking.

 

LOL allow me to retort.... MOST having nothing good to say. My comment was directed towards the others suggesting to not do it at all.


And my comparision to the R6 is an overall general statement...I am aware that the technology is different...that is my point. I have met others with the air box and they don't have the same performance.

And I will be getting it dyno'd when I am able to find the time.

 

Fair enough, I withdraw my last implied statement-was having a crappy day so maybe it influenced my tone.

I would be interested in what you find when you dyno. I understand most cars benefiting from the cold air systems and what not because they often do have very restrictive factory set ups, but on bikes the airbox has plenty of feed and the distance is so short and direct to the carbs that it doesn't really seem to make much difference in the flow.

But I know the Vmax benefits from it's setup because it moves an enormous amount of air and the HP gained is obvious. I would imagine your R6 with higher compression creates a more powerful suction so that might explain why it would improve more than an XJ.

 

********************************************************
********************DISCLAIMER!!!!!!!**********************
**************THIS POST CONTAINS INFORMATION ***********
**********THAT AWAITS MLEW, RICK, OR BIGFITZ *************
************LEVEL APPROVAL, JUST SPITBALL'N HERE**********
*********************************************************

I was under the impression that the biggest problem with pods was the problem with the chamber allowing the pressure on top of the slides to adjust quickly enough vs the vacuum through the venturi from the engine...

Basically these CV carbs require a low pressure baseline to compare the vacuum from the intake to the outside air. This baseline is what pushes the fuel out of the float bowl, as well as what lifts the slide...

This is usually not a problem with the factory airbox because the airbox allows for about 1atm of pressure of fresh (filtered) air to the throat of the carb. The vacuum doesn't transfer to the opening for the reference pressure because the airbox is so open that the vacuum basically stops at the end of the carb throat.

When pods are attatched, the filter is so close to the throat, that basically a low pressure is developed before the carb throat. Not AS strong a vacuum as the main part of the throat... but a vacuum none-the-less. This contained area behind the pod filter and before the throat creates enough of a vacuum (actually a depression, but that's fluid dynamics speak) in what I'm calling the "reference chamber" that the float bowl doesn't meet the design pressure specs to force ENOUGH fuel, through the jets.

The problem isn't that there's too much airflow through pods and the airbox is restrictive, the problem is that the pods actually pass the vacuum to the "reference chamber". Not only does this cause a lean mix due to low float bowl pressure, but it ALSO causes problems with lifting the slide... causing an even leaner mixture.

Re Jetting allows for more flow with smaller difference in pressures which is why some people have been able to re-jet and roll. Some PODS work just fine, I'd assume due to larger neck areas, larger interior volume, or just dumb luck.

This is just a theory, but a sound one (I have a degree in physics, and took special interest in fluid dynamics).

That is explains wy doing things like drilling a small hole to the top of your carb throat, then sealing the entrance off, OR putting tubes from this chamber through, and to the outside of the pods, works so well.

NOW. Instead of these two solutions, which undoubtedly have the flaw of allowing unfiltered air, rain water, or anything else in and out of your carbs (and into the float bowl!), and requires... unwanted... modifications (not to mention the tubes look ugly)... I am designing, (and soon testing) a pod adapter, which allows for outside air pressure to remain constant while still using pods, in a nice clean fitting and good looking manner.

but i'm new to this stuff so... i could ceratinly be wrong.

I'm about 90% certain that it would work, and be a nice clean looking fit for the PODS modification, which I LOVE the look of.

 

Now as for open headers, and 4-2 and 4-1 exhaust mods... I haven't looked into or thought hard about that yet. I have a feeling thought that it has a lot to do with backpressure maintaining the proper air fuel mix at the tail end of the exhaust stroke. But, I'll do some more research after I get my bike re assembled.

 

Well it's nice to know that the rest of us can just shut up now. MrPhys has spoken and three members have his approval. Everyone else just start asking questions because you are simply parrots or otherwise just don't know what you are talking about. Case closed.

EDIT: just wanted to add that the above is a bit of a rant. I took offense and responded with emotion, of course I know better and MrPhys and I have settled our differences over this issue. I misunderstood his approach and was too quick to judge. Please everyone who has a valid opinion or a good idea; go back to offering them

Fnet = m * a (is this why you are upset?) or things went wrong

MrPhys if your FD theory is correct, then why do bikes with full fairings like an R6 not demonstrate the same issues with pods??? If airflow, as you say, has NOTHING to do with it. And please explain, since you are a specialist in fluid dynamics, how exactly do sealed carbs, which have intervals of microsecond exposure to engine vacuum on one side and airbox atmosphere on the other, 'compare' the vacuum to the 'outside air' ?? I have college physics I and II under my belt (A's) and a 36 on the ACT in science as well as independent study of FD and extensive personal experience with mechanics. But I digress, you didn't want my opinion anyway...

 

All headers are open. Mufflers introduce restriction. Oh and just so you know BigFitz doesn't believe in backpressure so you better stop right now.

 

I said I was awaiting approval from those members. Not that I had it.

And yeah, the pressure is different in the top of the float bowl than it is in the carb neck. That is the reason fuel flows from the bowl into the the venturi. I didn't say it has nothing to do with airflow. In fact, it's quite the opposite. I said the problem isn't too much airflow.

I myself am not much of a believer that back pressure in the exhaust is as intimately related to carb and engine tuning as people seem to think.

I don't know if it's because the internet lacks tone, or what, but throughout your posts you seem to be kinda sensitive and insulting about all this. I said, several times it was just a theory.


Look at the throat to the carbs on your xj. See the little port on top? It doesn't have the engine vacuum on it like the main opening does. That port leads to a chamber just below the rubber on the carb right? That would be the high pressure side. The vacuum through the carb from the engine is transferred above that diaphram via drilled holes. When the throttle opens, a vacuum is applied above the diaphram, and the air below the diaphram remains at outside air pressure. this difference lifts the slide does it not?

Also from the chamber with outside air, there are drilled holes down into the top of the float bowl. When the needle rises out of the fuel jet, and the pressure in the carb body is below outside air pressure the difference in the float bowl air pressure and venturi air pressure sucks fuel through the jet. Yes?

So, i'd have to believe that the pressure difference in the two parts that control airflow and fuel delivery, rely on having a good solid outside air pressure to "compare" or "drive" the diaphram and fuel.

I am not so stupid as to act as though "I HAVE SPOKEN". I'm just saying, it makes sense.

Also, different carbs take their outside air from different locations. I am not familiar with any of them, so I can only answer I dunno, about the R6 question.

 

The issues with changing the air filter set up is due to the type of carb set up the bike has. when you open the throttle the throttle butterflys open, but the slides (which have the needle jets attached to them) don't open with them. The slides are lifted by pressure difference that exists between both sides of the slide. (Actually it not exactly both sides as the air cleaner side of the slide vents via a port at the back of each carb. So changing the restriction by fitting pods will effect the lifting of the slide, thus causing mixture change.

I would advise getting the bike running perfectly before changing to the pods as trying to modify the tune on a bike that has other running issues will be very frustrating as you chase your tail.

 

No not sensitive and not trying to be insulting. You have said before that you only trust two members, Rick an BF, and now since he has generously helped you Mlew has earned your good graces. The rest of us, according to you, have given you conflicting advice and basically misled you. I know there are some members on here who are eager to give advice who might have done that, I used to be one. But they ARE the exception. The majority of members DO know what they are talking about and are here to help-you seem to have overlooked that point perhaps because you don't listen well except to a few members who carefully parse their advice. I am sure if you would have payed CLOSE attention to what you were told you wouldn't feel misled. You made it clear in your previous post that you only expected those three members to be credible enough to determine if your theory was correct. Aren't you the physicist who understands FD? I acknowledged it was a 'theory'; and the 'I have spoken' aspect was in reference to the members who could sanction your theory-this my friend is evidence that you aren't paying close attention to what members on here are posting. I am sorry you feel I was insulting, but that is calling the kettle black as you are insulting every other member other than the three you have singled out.

To your pressure theory. I think you are overthinking this process. The accelerated air created by the engines' vacuum causes the pressure difference, nowhere in this system will you find matching outside air pressure that has an effect except at the entrance to the airbox or pods. If atmospheric air pressure was a determining variable then all of our bikes would go rich in bad weather and lean on a sunny day. The engine itself creates the pressure difference and is directly effected by how much air CAN and DOES enter each carb body via the air filtering device.

 

Bottom line... get the bike running like a Kenyan before you melt that airbox... Then tinker away. ( Personally (and my bike doesn't run so I know nobody cares what I think) I don't think three extra H.P. is worth the effort of removing the airbox.)

 

wow. yeah get it running right, then play with it.


Good luck with the podding.

 

I would like to add, in regards to the pod convo.

Outside air changes with weather and such don't affect the carbs as much because, as i said, the ouside air is the baseline, then the vacuum from the engine affects it.

in other words, the vacuum demands change with the density changes of the air. But because you are starting with outside air, then using it also as a way to manipulate the slide and float bowl pressures, the difference changes along with the initial air density change, with regards to weather.

In reality though, there is an effect on the running of the engine when weather changes, and altitude too! That is why people in very high altitudes, often times find they have to rejet. Or why your bike will run better on cold air in the fall vs hot air in the summer. Air densities. The design of these carbs is meant to work well in a certain range of air densities...

again why people at great or very low alititudes have to rejet.

 

Folks no matter how much sense our theories may make sometimes it comes down to simple solutions. I didn't do my mods intially for performance as much as it was to obtain a certain look. These carbs are complex and don't forget that there are a couple different versions.

When I bumbed up my fuel jets it did nothing for one of 3 reasons

1: My carbs still weren't clean enough
2: I wasn't properly seating the diaphram while replacing the carb cover
3: Which is the most likely........I hadn't changed the air jets to allow enouh air in the space between the diaphram and carb cover to allow the slide to operate properly.

I think it just makes sense that it's a simple fuel to air ratio issue when it comes to the complications with pods. There are never any write ups on folks changing the air jets and their results.

 

this is a amusing thread. all i have to say is pods are the greatest things that suck on a XJ bike

 

Ya.......suck air

OOOHH SNAP!

 

Just FYI MrPhys, the pressure difference that draws fuel into the air stream isn't the difference in the pressure from the engine vacuum and atmosphere. The Pdiff is created by the venturi itself, by way of Bernoulli's Principle.

Now I know it's specified for inviscid flow, but at low mach numbers, it's ok to use Bernoulli (i think). Basically, you don't have to consider the change in density in the fluid between it's two states.

The area of the venturi is smaller than the area of the carb opening. Given that the mass flow at the opening of the carb is equal to the mass flow in the venturi (because the mass doesn't go anywhere). Therefore, to get the same mass flow, the velocity of the fluid needs to increase to balance the equation.

Bernoulli's Principle basically states that the sum of the potential energy (pressure) and kinetic energy (velocity) is constant through a venturi. Therefore, as a fluid passes through the venturi, potential energy is exchanged for kinetic energy, so the pressure drops as the velocity increases. This "static" pressure is lower than the static pressure at the carb opening (where the "reference" pressure is) with draws air through the fuel circuits, in addition to raising the slides.

A hypothesis that I agree with (and that's not the same as a theory in scientific terminology) is that the flow at the carb opening that feeds into the fuel bowls/top hat/fuel circuits gets a lot of turbulence by ill fitting pods (that don't cover the "edge" of the back of the carbs) and non-straightened flow. That turbulence robs energy from the flow, and does it in a non-linear way wrt to mass flow. This is where the concept of a velocity stack can help to reduce this turbulence. In college, we actually used aluminum honeycomb to force air flow to straighten for an experiment.

As for pods working on other bikes, a lot has to do with the slides on CV carbs being vacuum operated. An R6 as MercuryMan stated is likely fuel injected, and the input of a mass air flow sensor is used to calculate and dispense the right fuel mixture into the airstream. That's why changing air filters on modern autos does not require any new programing or fuel mapping.

When it comes to "approval" of other members, realize that no member on this site have overall authority. In fact, I don't think the three you mention ever claim to have deep knowledge of fluid mechanics (theory, engineering, or simulation). You don't need that knowledge to be a great mechanic, and vice-a-versa. If you've got a concern with general maintenance, there's a group of members I would call experts. If it's extreme mods, like EFI, it'd be a difference group. That's what makes this forum great, not just some of the great experts you mention, but the depth of knowledge that many other members have.

 

that brought a tear to my eye, you guys are the greatest

 

I don't quite get it. When I wanted more power,got a bike with a larger displacement.But that's just me...'Course,ended up back on the 750-love that SECA.

However,has anyone ever tried bleeding oxygen into the airbox? That's what the desire is-right ? To burn more fuel per stroke. I'd love to see a dyno of it. Need a HUGE increase in jet size. I wonder what it would do to compression @ ignition? Or is that purely a function of the volume of air and the mechanical factor (cylinder volume at both ends of the cycle?

With more fuel AND more O2 to help it burn, there'll be more potential to kinetic energy without f'ing with NOX or turbo- correct?

To the more engineering-educated than I, would the waste gasses need a change in cam OR ignition timing? I would think that it's a variable which could be easily played with. Vary the flow rate of oxygen into the box. It'll get thoroughly mixed in there and displace air, which is a mere 21% O2.

Wonder what the amt. of unburned fuel is out the pipes? With YICS, bet it's fairly low. Need the bigger jets just to test the idea. Hmmmm,I've got that extra rack...

 

Oh the pods question is all so much fun. I have pods and it was a lot of work and I wanted to take a hammer to my head. But I got through it and my bike runs hard with them (neck and neck with a Maxim X 700 to 125MPH). I say go for it if you like detailed tuning and some problems to work through. They do look cool after all (like a bow tie) and if you take your bike in the direction of chopping or cafe they look even cooler. There was an earlier post about using two pods with a Y pipe to feed two cylinders or ram air which I really want to do but making it look right and still be functional is daunting. Anyway I say go for it your bike your way although not right away. Good Luck!

 

Aaaannnnnnyyyyyyy way. I thought the point of having a forum was to tell your success or failure, good or bad, and things that work or don't work. I get the physics of it all but not all of us have that kind of time to spend or really give two turds..... Lets not get caught up in trying to be right or proving someone wrong

 

I have to agree. The point of a forum is too have people come together and see what works and what doesn't. I really like the looks of the pods...that is why I'm doing it. I think that there might be less frustration with a setup that has 2 filters, both with 2 holes. Would love to see some pictures of how people have set that up. Fact of the matter is that if you want to do it...do it. After all it is your bike, and if it just takes some more time tuning then that's what it takes!

 

Permissiontolandfmx really was the only person to give creditable advice. Thanks for letting us know what combination worked for you! Anyone else use pods and want to give up their jetting combination?

 

Thanks Roverking!

 

for real?

..Ahem...

yep...

and on and on it goes... 8O brain pain sorry bout the physics dude. School sucks aaaaaannnyyway.

 

MercuryMan don't be so sensitive dude. Your continuing the trend of "who's right" lol.

Yes you a pod fan and I personally love to see it. All Roverkinkg and I are saying is that we need more people giving factual advice, real time progress and efforts. Believing something might work or conceptualizing what will be most likely to work is completely different to what makes your bike roll down the road.

We need not only to be sharing ideas, but experience.....not opinions or preference.

 

Well ok then.

I'm taking my pods and going home :arrow: :lol:

 

There's a thread on PODS success stories here:
http://xjbikes.com/Forums/viewtopic/t=2 ... rt=30.html

If you've got info on a combination that worked, there are many other members interested.

 

MercuryMan what combo did you use for your pod mod? And did you change your exhaust?

 

Want some factual advice. I have a Vance and Hines 4-1, K&N pods the ones with the taper, and a Dyno Jet stage three jet kit. Put on the exhaust installed the kit as instructed and tuned. The kit requires drilling the vent? holes in the slides to speed up their movement, putting in a new needle with adjustable length and three new main jet sizes. I have tuned it different ways depending what I needed due to altitude of where I was living at the time and what aspect I wanted to focus on. Now it is tuned for fun or peak performance all around. I lived at 400 feet altitude and was commuting 105 miles a day. There I had it tuned for best mid-range power and MPG. For me it was starting with everything set in the middle and tweaking first the needle height up and down then changing main jets and doing the needle again. After some time with that you get a knowledge of what does what and can then find the best combo. I have not changed any other jets and have not had any problems.

 

Thanks ManBot13. That link is exactly what I though we were trying to accomplish here.

 

i had great success with 4 into 2 open exhaust, stage 3 kit, patience to dial it in, thats it.

this pod thing seems to park alot of overcomplicated reasoning. the way I see it ............ more gas, less exhaust resriction equals more power. is it a world of difference? no. but it looks alot cooler in my humble opinion.

i think most of the horror stories with pods are directly related to other issues

 

no answers but a few questions.
does the intake valve closing make a shock wave that reflects back into the airbox and effect the other cylinders?
remember the hi-rise V8 intakes and the tuned length intake runners? could the same thing be going on in the XJ intake setup?
could the carbs really be seeing more intake restriction because of less filter area and no still air area with pods?
if the filter media is the same, the airbox shows more filter area to each carb, because they only suck one at a time thru that big filter.
how could you tune the outside cylinders to change mixtures as speed increases, all that wind that 1 and 4 see at 70, isn't there at 30, that has to change something

 

I agree. I wanted their approval because of their deep knowledge of real world xj stuff.

 

Polock while you are wise on much that is XJ. I think the carbs are hidden enough from air flow by being on the rear of the motor that at high speed it's pretty quite back there. The shock wave thing I consider and would love to investigate but that is beyond my brain I just make beer. I do know that these bikes were far ahead of any american bike tech for sure. The pods I have are tapered from the carbs back which is to separate the vacuum signal of each cylinder. But on thinking the factory air box could totally have a huge controlling factor in the overall performance of the engine. It really all boils down to efficiency, the engine is an air pump the more air it moves efficiently the more power it makes but if you increase air in you have to increase fuel in and also increase the air out. When I started my trip through pods my exhaust came with changeable restrictors that fit in between the header and the exhaust. I didn't use them for long. Oh this can become so complicated. Any Engineers specializing in air flow out there?