i've heard a lot of things about cone airfilters any truth?

i want to put cone filters on my bike and heard they are a horrible pain.
can anyone fully explain why? i think they look awesome and dont understand eho bag they can be

 

Its really quite simple. The CV carburetors fitted to XJ series Yamahas require a finite, regulated volume of air to acheive the proper manifold velocities for correct operation. Pod filters actually flow TOO MUCH air, necessitating re-jetting and creating tuning nightmares.

It's nearly impossible to out-engineer Yamaha, and gain any sort of advantage over the stock airbox/exhaust setup.

 

Re: i've heard a lot of things about cone airfilters any tru

thank you finally someone who said more than its going to be a hell of a task tuning it.

 

I think you can change the exhaust to aftermarket and rejet the mains a few numbers, but leave the stock air box in place. When your exhaust system rusts out you'll have no choice if you can't get the stock parts to replace it.

 

I have pods with stock exhuast but I do not know if the PO did rejetting. My bike runs fine but i would rather have the stock airbox to be safe.

 

Re: i've heard a lot of things about cone airfilters any tru

Normally, changing to an aftermarket exhaust does NOT require re-jetting, as almost ALL of the airflow restriction in the stock ATMOSPHERE > AIRBOX > FILTER > AIRBOX BOOTS > CARBS > INTAKE MANIFOLDS > CYLINDER HEAD PASSAGES > EXHAUST SYSTEM > BACK OUT INTO THE ATMOSPHERE is within the intake side of this air flow path, and primarily within the stock airbox/air filter. The stock EXHAUST system can flow more air volume than the stock INTAKE system allows.

Thus changing only the stock EXHAUST system, with no changes to the intake side of the heads, normally makes NO DIFFERENCE IN TOTAL AIRFLOW, and "no difference in total airflow" means "no difference in TOTAL FUEL FLOW" either, and thus bigger jets are not needed.

But once you start freeing up the INTAKE side of the entire system, you will produce more system airflow, even with a stock exhaust system (because, the stock exhaust system has the capability to flow more air through it than what the stock intake system allows).

This is why re-jetting is usually needed even if you keep the stock airbox and the stock exhaust, but use a K&N low-restriction filter, or even if you drill holes in the stock airbox, or leave the filter lid off.

All such actions free up the intake side airflow restrictions; the stock exhaust will move this additional airflow, and without providing addition FUEL flow to match the increased airflow (within limits, an engine will gobble up the maximum amount of airflow that it can; an internal combustion engine is actually just a self-powered AIR PUMP) then the engine will run "lean"---meaning not enough fuel to match the amount of airflow that the engine can (and now will) gulp.

Most pod type filters allow for vastly increased airflow, and thus require fuel re-jetting, and although no one really talks much about it, probably also require AIR JET changes to match the additional fuel flow, but since no one likes to deal with two parameters at once, it becomes a "tuning nightmare".

BUT, when you read all of the common symptoms of people who use pods, you quickly come to the conclusion that it's not possible to reproduce the stock "smooth in all rpm ranges" engine response. The reality is that you SHOULD be able to match it pretty darn closely, even with the increased airflow through the system, but ONLY changing the fuel jets isn't going to accomplish that. There are also air jets in the system, and they are there for a reason, as well as needle tapers and vacuum piston responsiveness issues.

 

It's not a horrible pain, despite what others may have said. If you have a little patience and know-how it's pretty simple to get it running like a top. There are many of us here who have done it successfully , and also many who have gotten frustrated, given up and talk poorly of pod filters.

 

I wouldn't exactly say, as Keven does: "Its pretty simple to get it running like a top."
My personal opinion, only ...
There's not anything easy about it and running like a top is out of the question.
You'll have to make a compromise according to how you ride the Bike.

Idle --> Off Idle --> Mid Range --> Wide Open Throttle.

The ideal situation is for the Bike to Idle and be able to get-out of the hole.
Then, accelerate through the Mid-range to Wide Open without suffering a complication in the Mixture that causes a Hesitation or an Unsatisfactory Mixture Condition that might be damaging.

Initially, upon abandoning the stock configuration for Pods the CONDITION is that the Bike is running TOO LEAN. Far too much AIR is introduced to the Mixture to have the Bike run right or run with a Critically Lean condition which would be harmful to aluminum parts.

This sets-up the first re-Jet.
A situation which needs to be corrected by adjusting the FUEL side of the Air~Fuel Ratio to correct an equation for which the:
(X~Fuel + Y,4~Air)= Z~ Ideal Ratio is maintained by Fuel Jets and a Finite (But unknown value) of Cubic Feet of Air per Minute (CFM) drawn-in through the AirBox Inlet and shared by the four Carbs.

Since the CFM is exponentially increased by PODS (along with introducing turbulence and an eliminating the stream shaping of the AirBax Boots which act as Velocity Stacks) a second Compromise needs to be considered.
The INTAKE AIR at each Carb does not have the same effect "Flowing" across the Top of the Emulsion Tube Outlet.
Less FUEL is drawn-up requiring the MAIN FUEL Jet sizes to be increased.
Although the MAIN JETS sizes are very easily altered to ALLOW a greater "Flow" of Fuel ... The Problem is actually getting the increased volume TO Flow up into the Intake Air Stream.

To achieve an Increased "FLOW" ... The Diaphragm Needle Height needs to be adjusted --> ALONG WITH --> an INCREASED Volume of MAIN AIR Surrounding the Emulsion Tube and that Air's ability to be Drawn through the Emulsion Tubes Metering Ports.

Without modifying the Emulsion Tubes and Increasing the Main Air Supply the Air Fuel Mixtures and Jetting are achieved through experimentation and guess work.

Most people who try it are still guessing.

 

i find it interesting how "afraid" of rejetting the on highway people are.

in the MX world where i hail from, the first thing we do is ditch intake and exhaust for bigger/better and REJET. we will rejet several times per season depending on weather and altitude changes.

+1

 

And how many carbs do you have on a MX?

In the case of the XJ, you have to calculate the expected jetting, put the new jets in all 4 carbs, test, adjust, test, adust ... and each time to test, you have to take the carbs off and open them up again.

And then the question of: what is gained with all this effort? From all that I have gathered, the only gain is the arguable cosmetic appearance of the pods (and the resultant ease of taking the carbs on and off) balanced against the loss of overall performance. It doesn't seem a fair exchange to me ...

 

Wrong. You do not have to keep taking them off of the bike repeatedly.

Where's the performance loss? I'm not claiming a tremendous gain, but I *certainly* have not seen a loss. Again, I must be the exception to the rule or be super lucky or be full of shizz. Maybe I should post a video of my bike starting and idling and revving with no problems/backfiring etc. Oh wait, already did that. Hmmm. There's gotta be a better explanation for my success.

 

To be clear: I have not done this.

Going by the experience of others, the rejetting with PODs provides an increased performance in some areas with decreased performance in others.

I fail to understand how you can switch jets in all 4 carbs without taking them off the bike. I'd be very interested in learning that trick.

 

I'm running stock jets, and for that I needed to take the carbs off exactly 0 (zero) times. Unless you count the initial removal for cleaning, then it would be 1 time. Either way, you do not have to remove them to "test, adjust, test, adust ...". But whatever, as you said, you've never done it. I have, on several bikes.

I'm not arguing for the sake of arguing. I have no reason to. I'm just saying it's not as much of a pain in the arse as people make it out to be. Believe what you want, I was just trying to be informative.

 

Kevin, I wasn't arguing. I was just trying to be clear. I have listened to those who have done it before here and the frustrations involved. I have read Chacal's bit in his catalog on using the pods which discusses how to calculate the probable jet changes that are the starting point and that as variables increase, so does the trickiness of the adjustment.

I am interested in hearing how it is you are able to keep from having to rejet even once in order to put pods on since they increase the air flow into the carb. That would suggest that the fuel mixture will become dramatically leaner, which isn't typically a good thing.

Please explain as personally, I think the pods look better than the carb boots and I'd love to be able to dispose of those infernal things.

 

Here's something to consider while you are making your decision.

Looking good is NOT better than running good.

Leave it stock and I can help you tune it to the razor's edge of fine tuning.
Put on Pods and I know there's nothing I can do to help you.

 

What Rick said.

Kevineleven, if you're running stock jetting with pods you don't do many highway miles or you'd have a holed piston or two by now. It's a simple scientific fact that eliminating the airbox allows unrestricted (and "unguided") airflow through the carbs. You ARE running lean, it just hasn't bit you yet. If your motor spends all its time in the low/midrange then a richer idle mixture is probably the only thing saving it. I wouldn't recommend running at 75mph for an hour...

 

Rick,
I have opted for performance over appearance, however, if there was a way to get appearance *and* performance without a major headache, I'll take it.

 

Hmmm ... a few weeks ago I started to write my thoughts on pod filters / jetting / aftermarket exhaust. It was a long article then I deleted the whole thing because it was full of too much detail. But in essence, you can't tune your engine properly with the pods. Engine tuning is a compromise but pods are designed for racing.

It's impossible because the whole system was set up to match all the parts. Intake, filters, carbs, rubbers, displacement, back pressure, etc. If you're installing pods then you ruin this fine balance. The result? You can have a kick ass top end (mine is running #132 jets at the moment, but she can live with #136 jets as well) but in this case below 6K she won't perform well.

Or you can have a decent low end and midrange but you will loose power at top. The best main fuel jets for low end / midrange in my case are the #124. Note a thing: I'm talking about 12 jet sizes. Let's try to make the proper compromise.

Not possible. If I don't want her run lean at top, I have to use the larger jet. But in this case she runs way too rich at the midrange. Ok, let's tune for midrange ... then she's running way too lean at top. What can I do? Acceptable midrange with a bit lean condition at top. In other words: I'm loosing some of the potential of the engine. However, it's still more than the original.

On top of this, you have to change the air jets. All the air jets. And you have to change the needles, diaphragm springs, probably you have to drill the vacuum holes in the slides and finally you will realize it can't be done properly. You can achieve a good 80 or 90 percent but not 100. Why?

Because this engine with those carbs are designed for a compromise. If you're putting on pods you push the engine to the racebike territory where low end doesn't matter. Top end, that's the only important thing. But we're riding our bikes every day and we don't using WOT too often. If you do ... go for pods. If you commute on her don't go for pods.

Yep, a stock bike can run with pods without rejetting but in this case she runs lean. No question about it. Did it, seen it.

Well ... one more thing. It is possible to tune them with the pods. But you have to install a fuel injection system on your bike. Otherwise ... those carbs are not able to serve all the needs of those engines when running on pods. Remember, you can achieve a good 80 percent but not 100.

 

Those who are still on-the-fence about: "To Pods; or Not to Pods", take this into consideration.
Yamaha needed to Maximize Profits during the time the XJ-Series Bikes were rolled-off the line and on to the boats.
They saved money on the "Build" where ever they could. That's why Hitachi Carbs adorn most of the XJ-Bikes sent to the USA.
The Hitachi Carbs are less-expensive "Knock-off's" of Mikuni's.
They were designed to assure Yamaha the USA Bikes would meet the burgeoning Environmental Standards in place at the time.
They simply do not modify very well.

What should you do?
If you really want to put Pods on a Tuned-up Bike ...
Begin by taking off the Hitachi's and getting a set of Mikuni's.
After you get the Mic's on the Bike, ... buy "Short-stacks and Pods."

 

And then spend the rest of your life tuning them............!

 

I'm not sure I want to get in the middle of this as I'm not not really interested in the performance or cosmetic advantages/disadvantages espesally after buying the chrome airbox side covers that my max was missing (thanks again Len!) but I do belive that there is more testing to be done in someones pvc intake idea for a single or dual pod set that may not create tuning problems or rejetting I'm sorry but I can't recall who did the post on this or how they made out in the end
Shaun

 

Re: i've heard a lot of things about cone airfilters any tru

It's all about the flow. Make available more air to an engine, and various technical issues aside, it will TAKE IN ("intake") more air up to the point where it cannot EXPEL ("exhaust") enough air to clear the cylinders of spent, combusted gases.

An engine is an AIR PUMP, a self-powered air pump to be sure, but an air pump nonetheless.

Air pumps can have restrictions either on the intake side, or the outflow side.

Yamaha in-line 4-cylinder air pumps have a greater restriction on airflow on their intake side. Free that restirction up, in any way, form, fashion, or manner, and the engine will suck up more air. And that will require more fuel, not due to magic, or personal opinion, or who-is-the-smartest-or-wisest-or-most-experienced or any other "beauty contest" considerations, but simply due to simple math and regular physics. ASSUMING the same fuel is being used (no switching between gasoline and alcohol, for example), more airflow is going to require more fuel flow in order to keep the proper air-fuel ratio in the proper range for both performance and engine safety/reliability issues.

That's not to say that your engine will instantly self-destruct, or not run at all, or not start easily, or "insert your symptom here" if you don't re-jet or make other modifications when you free up the intake side; it's just that you will likely experience some type or combination of issues that change or degrade some aspects of performance or engine reliability and durability (over some period of time) when you increase airflow without also increasing fuel flow.

By the way, leaning up the fuel mixture is a well-known way of making an engine produce more power. Lean mixtures burn hotter, typically because they burn more completely. The extraction of useful work is increased, thermodynamically-speaking, by having the fuel-air mixture at as high as possible a temperature (without resulting in pre-ignition or detonation).....the energy extracted therefore goes further in producing useful "work" (pressing down on the top of the piston crown) rather than being used to raise the temperature of the fuel-air mixture to the point of maximum combustion efficiency.

 

Running an XJ lean can and will result in holed pistons; look what happened to rpgoerlich's 550 Max. His PO didn't have the carbs fitted correctly and the motor holed two pistons in less than 8K miles.

Len's right you know, we don't just make this stuff up.

 

I've got over 7000 miles on the bike like this. I have done many 2hr trips on it. Thanks for your recommendation, but I'm doing just fine. No holed pistons. Sorry to disappoint.

 

Look, assuming that K-11 is telling the truth (and why would he lie, what would be the point in that? His claims have been consistent for many years now.), maybe in certain situations and combinations there is not a need to re-jet.............BUT, that would also mean, that due to perhaps the exhaust system being used, that the engine is not flowing much more (or any) more air than stock. Or, it already has bigger jets in it (750 carbs on a 650 engine, for example). Or, someone drilled out the stock jets but left the original size stamping on them. Or the fuel levels in the bowl are set way high, thereby "richening" the fuel mixture in a back-door kind of way.

Or something else..........in other words, the amount of airflow thru the engine determines the need for fuel, and nothing is ever going to change that relationship except God.

He does mention that he has noticed no real increase (nor decrease) in performance (engine power), which leads me to believe that there is not much increased airflow thru the engine for one reason or another, and which supports his insistence that re-jetting is not necessary in his situation.

 

i just realized that the pods that i am using, the rubber boots that clamp onto the carbs, slightly overlap the air jets. Maybe that is restricting K11s airflow. Instead of increasing the airflow, that overlap maybe in some weird magical way keeps the airflow fairly similar to having an airbox? It sounds unlikely but maybe thats just how it is. Just a thought.

 

you will have to rejet if you put the pods on your bike, so you might as well do some exhaust/muffler work why you have it apart, but I can say you will be able to feel some difference, because now you have 4 carbs breathing.. instead of 4 carbs fighting for air outta a 4 inch hole I have a maxim 650 with a stage 3 jet kit, 4 pods, 4 into 1 header, and custom built muffler, and my bike was just sicking fast with that done.. then came the motor work bore out, custom cams, custom pistons, cut & opened head up.... the bike is wicked fast,

 

I doubt that anyone is going to come-up with a recipe to solve the age-old problem of our Carbs being difficult to tune after abandoning the Airbox and installing Pods.
There are several issues and problems to overcome to get the Air~Fuel Ratio within the desired percentage to allow the Bike to run properly.
I am not aware of any process or formula that allows the modification to work as well as the stock set-up.
To my knowledge, the issue of the Carbs sharing a highly regulated flow of fresh air through the Airbox Inlet Port becomes the Major Problem to overcome when trying to adapt the carbs to Pods.

 

I am confused: what air jets are on the intake side of the carbs for the pods to cover that aren't normally covered by the boots that go from the air box to the carbs? Those boots go around the outside of the carb, just like the pods. On the XJ s that I have seen documentation for, there aren't any air jets you could cover on the intake side.

 

man ... you guys really know how to beat a dead horse!

 

I'm new to the forum...and new to the Maxim. But I am not new to Yamaha's and I have to concur. It's pretty hard to out do stock Yamaha for performance without it being a major PITA. Not to mention expensive.

 

I want to see it. The pressure drop at the airbox. I guess I'll have to do it myself- - take some tubing from my Manometer, one tube goes inside the airbox, after the filter- - thru the EGR hole, one under the seat outside the airbox.(in still air).

Then tape the water filled section to my windshield. That's gonna look stupid ! But at full throttle, and high RPM's, I should see the water move in the tubes, if there is an appreciable restriction.

But it's raining. . .

 

I suggest using something heavier than water.

 

A VERY dead horse...

 

It doesn't matter if you put-up a fence, install a well-lighted sign, have a Neon arrow blinking and pointed at the sign, have the lettering on the sign made in High Intensity L-E-D's and a loud speaker playing a loop of the voice of James Earl Jones saying: DANGER -- THIN ICE!

Somebody is still going to go through the ice.
Bank on it!