AIS vs Air Flapper

I'm a bit confused on these two guys and was hoping somebody might know the answer to the following questions.

(1) According to wrrdualsport.com: "If you go with an aftermarket exhaust, the AIS is no longer serving any purpose and will actually cause backfiring on decel. Time to dump it." So, since I still have the stock exhaust, sounds like I should leave the AIS alone?

(2) I thought I read that the airflapper should always be removed to "uncork" the bike, as it's just some EPA required thing. Is this true? Supposed to increase performance, by doing so?

(3) the instructions on wrrdualsport.com (http://www.wrrdualsport.com/tech-guide/air-intake/68-flapperrem) for removal looks good, but they leave me confused at step 6: "install the small rubber cap (1/8") onto the exposed brass fitting. If you purchased an AIS/Flapper removal kit from us, this cap is included." This sounds like I need to buy some kit/part? But it sounds like other folks do it on their own for free?

Anyhow, being mechanically challenged, any help would be much apprecoated, as usual!!

Thanks!
G4B

(1) According to wrrdualsport.com: "If you go with an aftermarket exhaust, the AIS is no longer serving any purpose and will actually cause backfiring on decel. Time to dump it." So, since I still have the stock exhaust, sounds like I should leave the AIS alone?

Myself, I'd install an FMF Q muffler (and FMF Powerbomb head pipe, too, honestly), install a fuel injection programmer, remove the airbox flapper, and then remove the AIS parts.
I suppose you could remove the AIS parts and do no further mods, but, what's the point of doing just that if you plan on keeping the bike all weak-feeling and corked-up?
And it is weak in stock condition, too, to keep you from destroying Earth.

(2) I thought I read that the airflapper should always be removed to "uncork" the bike, as it's just some EPA required thing. Is this true? Supposed to increase performance, by doing so?

That's basically it.
Have you ever removed the seat of your bike and taken a look at the air intake?
The flapper is a thing that flaps shut and closes-off three-quarters of the air intake area under certain condirions in order to reduce that wicked and nasty (sarcasm, there) intake noise.
In the process, intake air is reduced.
This is supposed to be the performance sacrifice you're supposed to gladly accept in order to keep yourself from making the ozone hole a lot bigger.
Remember the supposed ozone hole?
Where'd that one go?

the instructions on wrrdualsport.com (http://www.wrrdualsport.com/tech-guide/air-intake/68-flapperrem) for removal looks good, but they leave me confused at step 6: "install the small rubber cap (1/8") onto the exposed brass fitting. If you purchased an AIS/Flapper removal kit from us, this cap is included." This sounds like I need to buy some kit/part? But it sounds like other folks do it on their own for free?

Well, like a lot of things in life, you can either buy a ready-made kit to do the job, or, make a kit yourself.
When you remove the AIS parts, you need to plug important orfices that were once covered by the AIS parts.
No more tree-hugger AIS = needing a metal plate to plug the exhaust AIS port, blocking the fresh air source from the airbox, and a cap to plug the itty-bitty nipple that's left exposed on the throttle body.
If you're not whizz-bang with the wrenches, but a ready-made kit, and make sure it's for a WR-250R, not a WR-250F.

I've got the KEI AIS kit off of ebay.

Also, if you are messing with the airbox, you might as well ungut the intake hood to let that engine breath.

Especially if you are header/piping the motor.

YZEtc, thanks for all the info!!

Jeffpack, I'll have to check out ebay too. Being a super cheap mod, I want to do this very soon.

Yeah, I also want to ugrade the exhaust and get that programmer thingy, but need to save some money up first.

I'm gonna feel so guilty in the end knowing my dirt bike will be destroying the planet


Politicians

You might want to research the whole performance modifications list thing a little more before starting. These motors run real lean from the factory . Even if removing the air intake flapper added air to the air/fuel mixture, it doesn't necessarily improve the engine tuning (making it leaner).

You should keep the AIS intact as long as you have the stock exhaust/catalytic converter. The AIS services the CAT and there is no performance increase to remove it. It injects air into the exhaust to burn residue off the CAT and doesn't restrict air flow. An aftermarket exhaust with no catalytic converter makes the AIS and EXUP controller redundant, so no point in keeping them after you install after-market exhaust.

There is exactly one thing you can do to make more horse power - burn more fuel. It takes more air to burn more fuel, but in a normally aspirated internal combustion engine, the air/fuel ratio remains constant. Too much air = lean, too much fuel = rich. You need a fuel programmer to add more fuel and a little more air throughput to burn it properly, all managed by the ECU.

Removing these stock intake/exhaust related parts is cheap and easy, but as stand-alone modifications, they increase noise and hydro-carbon emissions but don't increase power. For me, it's not worth the effort to make my 250 sound like a 350. At some point, I'll probably be ready to spend the $600 or so to do the whole package - exhaust, programmer, AIS block-off kit, EXUP bypass kit for that extra 3 HP. My take on this subject is - all or nothing. I don't think I could even feel a 1 HP gain, so I don't want to piecemeal it. You get used to the new-found power pretty quickly and the buzz wears off. Then you're back to the real performance improvers - riding skill and less payload. I still need to work on both of those while saving my money for a small handful of extra HP.

Don't know what you weigh, but I promise that best cheapest performance mod is to lose weight.

When you treasure something, you build a shelter over it.

Boondocker wrote:

You might want to research the whole performance modifications list thing a little more before starting. These motors run real lean from the factory . Even if removing the air intake flapper added air to the air/fuel mixture, it doesn't necessarily improve the engine tuning (making it leaner).

You should keep the AIS intact as long as you have the stock exhaust/catalytic converter. The AIS services the CAT and there is no performance increase to remove it. It injects air into the exhaust to burn residue off the CAT and doesn't restrict air flow. An aftermarket exhaust with no catalytic converter makes the AIS and EXUP controller redundant, so no point in keeping them after you install after-market exhaust.

There is exactly one thing you can do to make more horse power - burn more fuel. It takes more air to burn more fuel, but in a normally aspirated internal combustion engine, the air/fuel ratio remains constant. Too much air = lean, too much fuel = rich. You need a fuel programmer to add more fuel and a little more air throughput to burn it properly, all managed by the ECU.

Removing these stock intake/exhaust related parts is cheap and easy, but as stand-alone modifications, they increase noise and hydro-carbon emissions but don't increase power. For me, it's not worth the effort to make my 250 sound like a 350. At some point, I'll probably be ready to spend the $600 or so to do the whole package - exhaust, programmer, AIS block-off kit, EXUP bypass kit for that extra 3 HP. My take on this subject is - all or nothing. I don't think I could even feel a 1 HP gain, so I don't want to piecemeal it. You get used to the new-found power pretty quickly and the buzz wears off. Then you're back to the real performance improvers - riding skill and less payload. I still need to work on both of those while saving my money for a small handful of extra HP.

hmmmm, thanks boondocker. Maybe I oughta wait too. I'm not actually that disappointed with the power either. I'm going to be getting a 2nd bike too - probably the WR450 - for my performance bike. The WR250R is gonna be my desert "exploration" bike. I've also found learning how to work the powerband can really make up for a lot as well.

2goose wrote:

Don't know what you weigh, but I promise that best cheapest performance mod is to lose weight.

A little under 170 ... so almost half the wieght of the bike

YZEtc wrote:

This is supposed to be the performance sacrifice you're supposed to gladly accept in order to keep yourself from making the ozone hole a lot bigger.
Remember the supposed ozone hole?
Where'd that one go?

Unfortunately, like ocean temperatures, it didn't go anywhere but out of the news. http://ozonewatch.gsfc.nasa.gov/ (Yeah, I know. What do those NASA hippies know? Fuckin' PhDs and all their science and measurement and observation stuff. Nothin' worse than cluttering up superstition and delusion with math and science."

Has anyone actually plotted the "performance" improvement of these modifications? Nothing like a few dyno runs to trash the engineering expertise of shade tree mechanics.

The guy I bought my WRX from did a crap load of these modifications to the bike, all of which I've returned to stock form. I saw him last week at one of our local "advanced riding schools" on his new punked-up R6. The thing has decals from every vendor who has screwed him out of his mom's money, but he still plods around the corners, chicken-strips his back tire on the straights, and brakes so hard for the hairpins he nearly gets run over by all of the riders trying to get by him. The schools all have no passing rules, anywhere but on the straights, so this dude is one of the many squidly characters who have to be flagged off of the course to eliminate the traffic jams behind them; sort of like the track version of those parades of Harley gangbangers on two lane roads.

The lady who runs one of our local schools, ex-AMA pro racer Jessica Zalusky, seems to think her bone-stock WRX does the job pretty well. When she decides to get to the head of the pack to flag them in, she doesn't have much trouble ripping by the rest of us on everything from me on my WR to squids on liter bikes. About a decade ago, when KR lived in Spain, he used to get his kicks riding an old RZ350 into the speed-limit-free Spanish mountains to shred the local squds on their liter bikes. You gotta hate folks who substitute talent for money. Why do they have to be like that?

Boondocker wrote:

You get used to the new-found power pretty quickly and the buzz wears off. Then you're back to the real performance improvers - riding skill and less payload. I still need to work on both of those while saving my money for a small handful of extra HP.

Ah man. You had to get mean, didn't you. That last 30 pounds of my diet plan has been harder to get rid of than wrinkles.

twday wrote:

You gotta hate folks who substitute talent for money. Why do they have to be like that?

That's some fine stinky bait!

The WR250X is my 17th motorcycle, and it's the only one that I've modified for power: muffler (most quiet I could get), header, fuel programmer, ripped out AIS, and probably this winter finally an airbox mod (if I ever decide which one!) And I've done all that for exactly one reason, passing other vehicles that park in corners on tight twisty back roads. And since the HP gain is so meager, it's probably only allowed me a few dozen extra passes to date. Those are expensive passes!

Am I a very fast rider? No, many of my riding friends are much faster. Am I a slow rider? No, I pass a lot of other riders.

But even though you seem hate me , I still like you .

I did all the mods to:
- make the bike simpler (less "stuff" to break, leak, etc.)
- perform better (20%+ improvement in HP/Torque is significant)
- make the bike lighter (between all the performance mods and a tail tidy, I've probably reduced the weight by 20lbs....and before someone says it, I have very little body fat, so I don't have 20lbs to lose!)

I couldn't care less about passing people, who's faster on the track, blah blah blah. I was tired of downshifting when going up hills on the freeway (good way to get run over....now I can actually accelerate up those same hills in 6th) and having the engine run too lean (it's much cooler running post-mods). Now it runs like it should, with no snatchy throttle, no lean spots, just solid performance.

To the haters....

-SM

I haven't read through the responses so pardon me if this has been repeated.

If you're staying with stock exhaust might as well leave the bike stock. Leave flapper and AIS alone.

If you "must" do the AIS you don't have to buy anything, but you will need to fabricate a block-off plate. There will be NO performance gain from removing AIS.
You will have less weight, but it's not going to be noticeable.


As for the flapper mod - once you have an exhaust and an EFI programmer just remove airbox door.

Removing airbox door is the biggest performance enhancer you'll ever "feel".

Just my 2 cents.....

twday wrote:

YZEtc wrote:

This is supposed to be the performance sacrifice you're supposed to gladly accept in order to keep yourself from making the ozone hole a lot bigger.
Remember the supposed ozone hole?
Where'd that one go?

Unfortunately, like ocean temperatures, it didn't go anywhere but out of the news. http://ozonewatch.gsfc.nasa.gov/ (Yeah, I know. What do those NASA hippies know? Fuckin' PhDs and all their science and measurement and observation stuff. Nothin' worse than cluttering up superstition and delusion with math and science."

Has anyone actually plotted the "performance" improvement of these modifications? Nothing like a few dyno runs to trash the engineering expertise of shade tree mechanics.

The guy I bought my WRX from did a crap load of these modifications to the bike, all of which I've returned to stock form. I saw him last week at one of our local "advanced riding schools" on his new punked-up R6. The thing has decals from every vendor who has screwed him out of his mom's money, but he still plods around the corners, chicken-strips his back tire on the straights, and brakes so hard for the hairpins he nearly gets run over by all of the riders trying to get by him. The schools all have no passing rules, anywhere but on the straights, so this dude is one of the many squidly characters who have to be flagged off of the course to eliminate the traffic jams behind them; sort of like the track version of those parades of Harley gangbangers on two lane roads.

The lady who runs one of our local schools, ex-AMA pro racer Jessica Zalusky, seems to think her bone-stock WRX does the job pretty well. When she decides to get to the head of the pack to flag them in, she doesn't have much trouble ripping by the rest of us on everything from me on my WR to squids on liter bikes. About a decade ago, when KR lived in Spain, he used to get his kicks riding an old RZ350 into the speed-limit-free Spanish mountains to shred the local squds on their liter bikes. You gotta hate folks who substitute talent for money. Why do they have to be like that?

If you like your WR-250X stock, fine.
I thought it felt weak due to those EPA regulations.

So let me get that right, the WR runs close to lean by factory specs, and by opening the flapper it'll run even leaner?

So the stock computer will not be able to add more gas to the mixture, to get it back into specs, to compensate?

Computers on cars can do it up to a certain point. If you add a K&N filter to your car or truck, the computer's range is usually big enough to level the mixture out. That does not count for the WR?

If you keep the stock exhaust, I believe the stock Yamaha ECU can compensate enough to not put the bike in the danger zone if the flapper mod is done.

However, once you uncork the exhaust, and allow the free flow of air through both the intake and the exhaust I don't believe the Yamaha ECU is capable of that much range of compensation.

The theory is just that.

As I've repeated quite a lot - I've not read anywhere (here, ADVrider, Thumpertalk, or Supermotojunkie) about anyone seizing or in any way damaging a wr250r/x due to overly lean conditions.

Most people however chose to not be the first, and chose to add the fuel programmer when they start modding the bike farther away from stock.


The choice is 100% yours as to how far you want to push the envelope.

WRXR wrote:

So let me get that right, the WR runs close to lean by factory specs, and by opening the flapper it'll run even leaner?

So the stock computer will not be able to add more gas to the mixture, to get it back into specs, to compensate?

Computers on cars can do it up to a certain point. If you add a K&N filter to your car or truck, the computer's range is usually big enough to level the mixture out. That does not count for the WR?

The factory Yamaha computer doesn't have and ability to see the increased air coming in. It's what we call a 'speed density' type system. It has no air meter type sensor like most cars do. It also is a 'open loop' type system and that means that it doesn't have an o2 sensor that it reads and makes adjustments for (fuel trims). The system is super super simple and only calculates how much air it thinks is there and adds what it thinks is the right amount of fuel for that air.

So when you increase the airflow into the engine, it get's even leaner than stock because it doesn't know the extra air got in there.

When I bought my WRR the previous owner had already removed the AIS and EXUP unit becausehe put an FMF PC4 on it. I wanted to go back to the stock exhaust because the FMF was just annoyingly loud to me. I removed the flapper because I wanted the room under the seat for electrical components (relay, terminal block, etc) for heated grips, and later maybe heated gear, gps, whatever. My seat of the pants experience tells me the bike runs the same before and after the flapper removal. The only difference I can tell is now I can here intake noise from under the seat that I didn't before. I kept the parts and it will be easy enough to put them back.

If you want free seat-of-the-pants difference, the only way you get that is with taking the airbox door off completely.

The flapper mod won't make your bike a performance-king to be sure.

Like I said I didn't do it for performance. It was a space issue for me. I only mentioned it didn't improve performance because I hear a lot of people say they did it for performance gain.

Z1500 wrote:

WRXR wrote:

So let me get that right, the WR runs close to lean by factory specs, and by opening the flapper it'll run even leaner?

So the stock computer will not be able to add more gas to the mixture, to get it back into specs, to compensate?

Computers on cars can do it up to a certain point. If you add a K&N filter to your car or truck, the computer's range is usually big enough to level the mixture out. That does not count for the WR?

The factory Yamaha computer doesn't have and ability to see the increased air coming in. It's what we call a 'speed density' type system. It has no air meter type sensor like most cars do. It also is a 'open loop' type system and that means that it doesn't have an o2 sensor that it reads and makes adjustments for (fuel trims). The system is super super simple and only calculates how much air it thinks is there and adds what it thinks is the right amount of fuel for that air.

So when you increase the airflow into the engine, it get's even leaner than stock because it doesn't know the extra air got in there.

Thanks, excellent answer!