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I took my bike to the shop last week for an inspection and new rear tire. Me and the write up guys discussed a few things. He was a fan of a debaffle, one for the sound and also for opening up the exhaust. I showed him the intake mod, and he said that it was a great idea, giving more air to the engine. I told him I wanted to get a BAK, but he said that it was a waste. If I could get a K&N for the 900, I would get just as much air in. He said that you could only get soo much air through the throttle body intake.

I cured that problem today, and made myself a K&N filter, stock frame and old K&N that I had lying around. $5.49 for a pack of JB Kwik set. Brave being that I did not have another filter close. Dremel tool and time. I am going to marble the air hoses as soon as I fined a marble or two.

I have one question. For those of you that have made this type of mod, how much difference do you see with a fuel controller? Not on paper, but real life, on the road difference.
 

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I'm not sure why the guy at the bike shop would tell you that it was a waste of time getting the BAK. The BAK and the Arlen Ness Big Sucker both use a K&N filter and the difference in performance on my bike was dramatic. The air inlet on the stock intake is tiny and at the back of the unit near the hot heads.

I'm interested to hear how you're home made mod increases the performance. If it works it would be nice to know as a "Low Buck" modification for other riders.

As far as the fuel management system is concerned it made a nominal difference in performance (mostly because it wasn't running with the factory lean setup). The biggest advantage to the fsm is the ability to add or take away fuel through out the power band. I was able to adjust mine until I got rid of most of the annoying exhaust pop.

Also, good luck finding a marble. :) I searched every toy store, Wal-Mart etc. in my area with no luck. I ended up taking the hose off and bringing it to an industrial supply store and fitting a ball bearing. I guess kids don't play with marbles anymore. :)

Let us know how your mod worked.

Happy riding.
 

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I gotta ask ...I've read other threads that mention "marbleing" ...

Where are you putting this marble and what benefit does it provide??? It's not intuitively obvious to me why we would do that. Obviously it's meant to block something but ....what???
 

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Low buck air flow: Measure the air inlet and transfer it to the area under the idle screw. I used a Rotozip to cut the hole. Use the existing rubber to finish it off. Block off the OE hole with a piece of aluminum (I used an old gutter) and two pop rivets.

 

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FWIW...
I haven't done this yet (don't need to on a stock bike :( ) But I've been told by the "old school" guys that you can use a wire nut if you can't find the right sized marble....
 

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I originally used a wire nut versus marble; I couldn't afford to lose any more of my marbles. I've since taken an alternate route. I got 6-5/8" Bypass Caps (about $2) from the local auto store and removed all of the hose plumbing from the airbox, air switch and the cylinder heads. Since the air switch uses the hoses to keep it on its mount a short piece of vacuum line on the mount stops the switch from sliding off. Don'y disconnect the electrical connector or you get a fault.
 

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Low buck air flow: Measure the air inlet and transfer it to the area under the idle screw. I used a Rotozip to cut the hole. Use the existing rubber to finish it off. Block off the OE hole with a piece of aluminum (I used an old gutter) and two pop rivets.

I have always loved your HD cover, never could find one.....anyways, awesome mod. I think I'll do it over the winter months. How does it get any air in the present location btw? (behind the air cover).
 

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Evidently the slotted cover was only made from 2004-2007, I ordered mine late 2008. I checked some HD sites and I think the last one was found hanging on a shop wall in Kentucky.

Air comes in through the relocated rubber snorkel under the idle adjuster. At one time I wanted to compare air temps at the filter using the OEM inlet location and the new location. Decided to permanently close off the OE inlet while I had it apart. I still want to compare ambient temps to temps at the filter media but never get around to it. No matter what, force feeding air into the box has to be better than sucking air from between the cylinders. The HD cover has a black dish behind the chrome cover to make it look functional - all show, no go. The dish actually has the stud that bolts to the OE cover and the chrome piece screws to the dish.
 

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I took my bike to the shop last week for an inspection and new rear tire. Me and the write up guys discussed a few things. He was a fan of a debaffle, one for the sound and also for opening up the exhaust. I showed him the intake mod, and he said that it was a great idea, giving more air to the engine. I told him I wanted to get a BAK, but he said that it was a waste. If I could get a K&N for the 900, I would get just as much air in. He said that you could only get soo much air through the throttle body intake.
I cured that problem today, and made myself a K&N filter, stock frame and old K&N that I had lying around. $5.49 for a pack of JB Kwik set. Brave being that I did not have another filter close. Dremel tool and time. I am going to marble the air hoses as soon as I fined a marble or two.

I have one question. For those of you that have made this type of mod, how much difference do you see with a fuel controller? Not on paper, but real life, on the road difference.
I hate to pop the inspector's bubble, but that's a load of bovine fecal matter!!! I did the K&N mod that you described and ran it for a year. I also opened up a space on the front of the air box to help with more air (simular to Mr. Baitis). About two weeks ago I installed an Arlen Ness Big Sucker. Dude, no comparison what so ever. The differance really impressed me!!! No matter what speed or RPM I'm running, when I hit the throttle, I get more juice than before. It's a whole different bike. I agree the K&N is better than stock, but even K&N recognizes the differance is mnimal. This is a big reason why they don't make a filter for the 900 (I've had this discussion with them). In time you'll want to look into a better air intake if you want more juice in your ride. you only need ask yourself one question... "Do I impressively feel the differance?" I thought I did when I did the K&N, but after the Big Sucker.... (((BTW, I run K&N in my Malibu and Silverado and really like the filters for that application.)))) Lastly, if you increase air in, you'll deffinately want to increase air out. That's when it gets really sweet. :D :D :D
 

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Just an FYI - the filter in the Arlen Ness Big Sucker is a K&N. :)
 

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The bike has a valve that upon deceleration, opens up and sends extra air to the exhaust. This action provides extra oxygen to ignite unburned fuel vapor coming out of the exhaust (emissions equipment, environmentally friendly). The marble, when stuffed in the hose coming out the top of the air intake, keeps this air from going to the exhaust, thereby reducing the ignition of the unburned fuel. There is still some popping, but by limiting the extra air intake, it's supposed to reduce it somewhat.
OK, I am confused as usual. Where exactly does this hose send the air into the exhaust system?

My understanding is this is part of the PCV(Postive Crankcase Ventilation) system. This burns the oil vapors coming out of the crankcase. The ECU controls the air valve allowing air into the engine(from the filter housing), and then it comes out from the rear of the front cylinder(through a PCV valve) from the crankcase back into the filter housing to be burned.

If anyone is familiar with auto applications, if the system is plugged, bad things will eventually happen. The engine will breath, usually through a blown seal.

So what am I missing?
 

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Just an FYI - the filter in the Arlen Ness Big Sucker is a K&N. :)
I fully realize that and am happy that it is. Like I said I have K&N filters in my 2 vehicles. The problem isn't the type of filter, but rather the size of it. The space the intake has to draw air from is restrictive. For the intake to get the maximum effect of air, the filter surface has to be much larger to allow the air to get through. With the 900, the air is drawn in through a space not much bigger than the intake jets with a filter surface area that isn't all that much bigger (even if you removed the cover and secured the filter, the space would still be restrictive compared to the larger aftermarket air intake systems). The idea of the larger filter is to let more air in and with a ram air system, it's facilitated even more. The OEM air box for the 900 is a poor design at best. However the rest of the bike rocks!!! IMHO
 

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OK, I am confused as usual. Where exactly does this hose send the air into the exhaust system?

My understanding is this is part of the PCV(Postive Crankcase Ventilation) system. This burns the oil vapors coming out of the crankcase. The ECU controls the air valve allowing air into the engine(from the filter housing), and then it comes out from the rear of the front cylinder(through a PCV valve) from the crankcase back into the filter housing to be burned.

If anyone is familiar with auto applications, if the system is plugged, bad things will eventually happen. The engine will breath, usually through a blown seal.

So what am I missing?
I replaced my aftermarket pipes with Cobras. I don't recall any hose being connected to the exhaust (OEM or otherwise). When I marbeled the hose, there was no differance with the popping. I agree the hoses have to do with crankcase ventilation (as stated above).
 

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There is two hoses one is for the crankcase the other that they marble is for a air intake system to add air when you let of the throttle to the exhaust ,that's what makes the popping that some don't like.To me the popping is just fine so I leave it stock.there is no benefit to marbling other than getting rid of the popping.
 

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There is two hoses one is for the crankcase the other that they marble is for a air intake system to add air when you let of the throttle to the exhaust ,that's what makes the popping that some don't like.To me the popping is just fine so I leave it stock.there is no benefit to marbling other than getting rid of the popping.
Thanks xcbullet. I can see where plugging that hose would trick the inlet air pressure sensor into giving the bike more fuel on deceleration.
 

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Plugging the the top hoses does not change fuel delivery or affect power; it merely stops fresh air from being injected to the exhaust stream for emissions purposes. The only crankcase ventilation is through the hose at the bottom of the front jug behind the coils that connects to the bottom of the airbox. Don't overthink the Kaw, it's a crude system by today's standards.
 

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Discussion Starter #19
I hate to pop the inspector's bubble, but that's a load of bovine fecal matter!!! I did the K&N mod that you described and ran it for a year. I also opened up a space on the front of the air box to help with more air (simular to Mr. Baitis). About two weeks ago I installed an Arlen Ness Big Sucker. Dude, no comparison what so ever. The differance really impressed me!!! No matter what speed or RPM I'm running, when I hit the throttle, I get more juice than before. It's a whole different bike. I agree the K&N is better than stock, but even K&N recognizes the differance is mnimal. This is a big reason why they don't make a filter for the 900 (I've had this discussion with them). In time you'll want to look into a better air intake if you want more juice in your ride. you only need ask yourself one question... "Do I impressively feel the differance?" I thought I did when I did the K&N, but after the Big Sucker.... (((BTW, I run K&N in my Malibu and Silverado and really like the filters for that application.)))) Lastly, if you increase air in, you'll deffinately want to increase air out. That's when it gets really sweet. :D :D :D
I have been looking at the BAK for a while, just have not dropped the cash yet. When I completed the air box mod like others, I noticed that I had more kick from the engine. I did not close off the original location, so I esentially doubled the amount of air coming in, plus the front opening is forced in. I debaffled pipes and so I should be getting more air out, limited only be the built in catalyst.

The good thing with these mods is that they basically cost you time. A new intake, exhaust and Fi controller is a grand, easy. The bad thing is that it is hard to measure the benefits. Seat of the pants results are relative to how good you feel about the mod. Truth be known, all of these home made mods only add minimal HP, eventhough we all say how much faster and stronger our bike is afterward. I think at one point I will go to a BAK and maybe one day some new pipes and Fi controller. I will report fuel mpg this week with the [email protected] mod.
 

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After a close examination of my LT and looking at the SM I am convinced I was right this is the PCV system.

This is how it works.

1. The air switching valve is the inlet for fresh air for the engine. From the airbox to the ASV it goes into both valve covers and in both heads where there is an air suction valve, a one way reed valve, it lets air into the engine but not out. The faster you go the engine requires more air to breath, so the valve has to be open more.

2. The air outlet hose comes off the back of the front cylinder and sends the crankcase exhaust back to the airbox to be burned.

When you marble you are effectively cutting off the engines inlet supply of air. The engine has to breath, somehow, just like us. Inhaling and exhaling. I do not see anyway this will effect popping noises(lean misfire). I do not see how air is being injected back into the airbox or intake, because of the air suction valves are one way check valves. It is definately not being injected into the exhaust system except after being burned through the engine.

This seems to me more like Voodoo mechanics and I would encourage any one of you who have done this foolish procedure to talk to a FACTORY trained Kawasaki technician(who understands how these systems work) and see what he has to say. You could quite possibly damage your engine and you will definitely LOOSE power.

If you don’t want oil in your air filter I posted what we do on Buell’s. Most bikes have the same problem.
 
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