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Discussion Starter · #1 ·
Well I must admit that I was a little surprised that this mod has not already been posted as it has been mentioned a few times, but I couldn't find and didn't know what it was! Unfortunatley, I had to spread my search to include other websites, something I thought I would never have to do!!! :p

So, what is the Kleen air system, and what does it do?.......I can't really say, because I'm not a mechanic!!!!! Ask someone like Spooph! ;D

The reason I did this mod was because of too much snap,crackle and pop when off the throttle after my new exhaust mod. Apparently the Kleen air system injects air into the exhaust to help burn off excess fumes/fuel(please feel free to correct me and I will change as needed.)
What really surprised me was how easy this mod is to do, even for someone with no mechanical experience. This is basically on par with removing the snorkel!!

Items needed for mod: - tools to remove fairings and fuel tank
- 5mm vacuum plugs
- 1/2" water caps x 2
Time frame - about 1 hour - And I was very careful!

Get yourself set up, I found if you have good music, your computer ready and skittles, everything works well!! Excuse the messy shed!

You can see my next project is waiting for me(BBQ!) Thats for the weekend!

Obviously, the first thing to do is make sure your ninjette is warm before you start taking her clothes off!


Start by removing the hose that mounts to the top of the air box

Keep the gold clip.

Follow the hose towards the front of the bike and remove from that end, keeping the gold clip again.



You will be left with this.

Whatever this thing is, it has to go also, and the connected hoses and bracket will also be removed. The thinner vacuum hose leads to a t-junction that branches to the carbie and the fuel tank. Block this off with a 5mm vacuum cap. (Sorry, no pic!)
You will now have two open ports on the engine and the airbox, cap these off with the 1/2" water caps using the gold clips you kept from earlier to hold them in place.







And you're done! Put everything backtogether and make sure it runs!!!!

You should have something like this left over.


Hopefully this will work! It was a bit late when I finished, so will do an update and video on the weekend
If you have any questions, don't hesitate to ask someone else!!!!! ;D, cause I can pretty much guarantee I won't know the answer!!
Apologies to Indie, who thought he would have to help me on this one, bad luck Princess!!
 

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Re: Kleen air system removal - Pic heavy!

I don't think the breather should be plugged completely. I put K&N air filters on the openings after removing the air box.
 

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Re: Kleen air system removal - Pic heavy!

I do not think this particular mod is necessary. What this mod does is prevent upper cylinder head vapors from escaping which can lead to pressure build up in the upper cylinder. This mods removes the system that allows those vapors to be pulled into the carb and burned off. When the vapor pressure in the upper cylinder reaches a certain psi it pushes open the vacuum switch (black part) and the vapors are pulled onto the air cleaner housing and into the carb to be mixed with air and fuel then burned off. That is why you may see oil from time to time in the air cleaner housing. The same process is done on autos. They call them PCV (Positive Crankcase Ventilation) valves. Those gases have little or no effect on combustion, but the pressure that is created in the upper cylinder can lead to possible damage to the head over time. If you want to you can run a longer hose from the air suction valve (silver part)down away from the engine and rear tire to allow the air to escape, but it might not be as effective as having it vacuumed off. Even if you had air filter pods, it is a good idea to let the upper cylinder vapors escape or be pulled into the combustion system. The popping, crackle or knocking sound you are hearing is probably due to the carb being too rich (un-ignited gas being burned or ignited in the hot exhaust manifold or carbon build up in the combustion chamber: heat can also produce the same noise if the exhaust is not muffled or baffled correctly.), not the clean air system. Try adjusting the pilot screw or idle mixture screw. If you are looking to get more air into the stock air box, try drilling about 4 or 5, 1/4" holes in the rear of the air box. (assuming you have already shimmed the needles)
 

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Re: Kleen air system removal - Pic heavy!

Yeah i don't feel it's necessary either. When you have the pods and the K&N air filters on the uper cylinder AND the crank case you can not ride in the rain. It will pull in all sorts of moisture. I did a R-0990 change out and it's not practicle for the area that i live in now. Maybe down in California but not in Washington. Plus i could not give my bike enough fuel with the bigest main jet that came in the stage 2 kit. So i put a peice of plexiglass on the top and bottom to restrict air flow a little bit. But that bike was a lot of fun with it on.
 

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Discussion Starter · #5 ·
Re: Kleen air system removal - Pic heavy!

Ok guys, Thanks for your input! As I said at the start, both Indie and I have searched many websites looking for the answer to this issue, and this mod keeps on popping up, even here.
I will look at adjusting the idle mixture screws(yes, I have it shimmed) and see what we got.
RacerX - what size is that pod filter, and as sailor said, does the pod need protection from the elements?
 

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Re: Kleen air system removal - Pic heavy!

zandit said:
Apologies to Indie, who thought he would have to help me on this one,

AAAAhhhh what was that phone call i had, im sure it was some one in need of a little advice.
 

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Re: Kleen air system removal - Pic heavy!

If I may throw my two cents into this discussion...

The Crank case ventilation mod as shown by Zandit will help remove oil vapor from entering the carbies and ultimately the combustion chamber, potentially lowering your effective octane. However as stated by Blue Ghost and Racer X it will lead to excessive pressure in the crank case which will try and find another way out, normally the filler cap or oil level stick.

The best way to achieve the same effect and still allow the crank case to vent is to have a Y neck installed into the exhaust before the mufflers. It needs to be setup in a way that the passing exhaust gas creates a vacuum which will draw out and "burn off" the oil vapor on its way out.

I have seen this setup run on a few drag cars but in saying that I am not sure how much filthy oil vapor the 250 breaths in...

Racer X might be able to comment on the potential gain, it might only be minor but when your chasing thousands of seconds off your time any change will help.

Gazza
 

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Re: Kleen air system removal - Pic heavy!

The way the stock system seems to work . I have to think about it but I THINK it goes like this.
One hose is hooked to the carb side of the air box and goes to the top of the engine. The other hose is hooked to the Dirty side of the air box and goes to the bottom of the engine. There is a valve that closes the top hose going to the valve cover when the bike is running .
When you accelerate vacuum drops and the valve opens . This lets the flow through and pulls air through the engine removing dirty vapor and pressure allowing it to go into the air box and get burned . Yes oily air is bad . Mostly for the environment so it is not just let to go loose .
For OFF ROAD applications normally it would be vented outside .

For an engine that revs easily past 12000 rpm crankcase pressure is very bad for performance.

I run this setup for the street keeping the valve . But Smooth bore carbs don't have vacuum ports so I cant use the valve . Or fuel valve for racing
 

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Re: Kleen air system removal - Pic heavy!

So Racer X for those like me who mainly use their bikes for commuting and the weekend trips to the mountains. What would be the best when I'm able to get a slip-on? I understand if you remove this it eliminates the backfire from the exhaust.
 

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Re: Kleen air system removal - Pic heavy!

The Clean Air System operates by using the carburetor intake manifold vacuum through the vacuum switch valve to create negative pressure in the crankcase. It then carries the crankcase / cylinder vapors to the combustion chamber to be burned. The vacuum switch valve of the clean air system also serves to function as a pressure relief point for crankcase / cylinder head vapors, in the event of an internal engine malfunction (much like the PCV system on a car). If this occurs, excess vapors are vented through vacuum switch valve into the air cleaner. One symptom of crankcase vapors flowing into the vacuum switch valve is oil residue in the air filter housing.
When the engine is running, a certain amount of combustion gas escapes past the rings into the crankcase; this is normal. When the engine is at idle, vacuum overcomes the spring tension of the check valve and causes it to move inward and restrict vapor flow into the intake. When the bike is cruising and vacuum is lower, the spring tension moves the check valve away from the seat, allowing higher flow of crankcase vapors into the intake. Control of crankcase vapor flow is used to prevent excessive amounts of vapors into the intake at idle speed. This could cause rough idle or incorrect idle speeds.
The air suction valve is on top of the valve cover and is attached by hose to the vacuum switch valve. The position of the air suction valve allows it to pull vapors from inside the engine without sucking oil from the crankcase (reeds on the underside of the air suction valve deflect and help separate droplets of oil from the blow by vapors). A hose connects the vacuum switch valve to a vacuum port on the air cleaner housing. This allows the vapors to be siphoned directly into the engine without gumming up the throttle body or carburetor.
Because the clean air system pulls air and blow by gases into the intake manifold, it has the same effect on the air/fuel mixture as a vacuum leak. This is compensated for by the calibration of the carburetor or fuel injection system. Consequently, the clean air system has no net effect on fuel economy, emissions or engine performance -- provided everything is working correctly. Combustion gases consist mostly of carbon dioxide and water vapor, but do contain small amounts of unburned fuel and other contaminants. Water and fuel vapors in the crankcase can react to rapidly break down and shorten the life of engine oil. In addition, these vapors contribute to the formation of sludge in the crankcase. The worst case scenario if the Clean Air System is plugged or blocked is blown seals, blue exhaust smoke, power loss, poor drivability, excessive carbon build up in the combustion chamber & possible head damage.

WARNING: Removing or disconnecting the clean air system in an attempt to improve engine performance, gains nothing and is illegal. EPA rules prohibit tampering with any emission control device. Disabling or disconnecting the clean air system can also allow moisture to accumulate in the crankcase, which will reduce oil life and promote the formation of engine-damaging sludge.

Backfire, popping, knocking, crackles...etc. is caused by a too rich or too lean carb. The amount of crankcase vapor on the carb and combustion system is nill, because of the calibration of the carb and the vacuum switch valve. Hope this has helped somebody.
 

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Re: Kleen air system removal - Pic heavy!

Great info Blue Ghost. If someone has issues with the backfireing. poping, etc. it would be best to adjust your carb.
 

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Re: Kleen air system removal - Pic heavy!

Hey im Not a mechanic but i dont see how the crank case can build up pressure due to this mod. The crank case hase its own breather going to the air box. All pressure that would come from this mod will be vented via crank case vent. Just my thoughts.
 

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Re: Kleen air system removal - Pic heavy!

Thank you for explaining it properly .

Right now I have filter pods . and a small filter on the clean air valve . And one on the crankcase port. I guess I will change to an air filter that is not two separate filters .. And run a hose from the lower crankcase port to the air filter. That way I have the system hooked up properly.
 

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Re: Kleen air system removal - Pic heavy!

Indie, not all of the pressure will come out of the crankcase breather. Pressure as will heat and vapor will also travel up to the top of the cylinder ( cams and valves) via oil passages (oil pump). Most of your heat and pressure will be generated at the top portion of the cylinder head. maybe I should have been more clear when I said crankcase / cylinder. I was not just referring to the crankcase only. I was trying to give a generalization to the whole clean air system and how it operates. I do believe however in my first post on this mod I said ,"What this mod does is prevent upper cylinder head vapors from escaping which can lead to pressure build up in the upper cylinder. This mods removes the system that allows those vapors to be pulled into the carb and burned off." Sorry for any confusion.
 

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Re: Kleen air system removal - Pic heavy!

OK
I found a K&N filter to use with the new ninja . It is a dual inlet pod # R0990. I can run a hose from the bottom of the filter between the carbs.To the crankcase breather and get proper scavenging of air from inside the engine through the clean air valve with a small filter on that .
http://www.knfilters.com/search/product.aspx?Prod=R-0990
 

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Re: Kleen air system removal - Pic heavy!

Zandit...

1.) Thanks for the great write up and pictures. You're right, most people don't deal with this EVER, so this is a good addition to the knowledge base, and the conversation along with it. :)

2.) I agree with Ghost and X, this is illegal, and bad for the environment. That the valve train should be vented, and that the performance gains are negligible... BUT what I will be doing is the exact same thing as X. A pod filter on the valve cover to allow it to breath, and plug the airbox side like you did in your write up. I'm doing it quite simply to clean up the bike. Eliminate hoses and you don't have to worry about where they go when you take them of, eh? :p A simple machine is a beautiful machine, not to mention the weight savings!!!!

Keep 'em coming dude!
 

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Discussion Starter · #19 ·
Re: Kleen air system removal - Pic heavy!

Yeah, wasn't expecting this kind of reception!!!!!
I was just hoping to cruise through this forum and make the odd comment here and there, but NO....you guys had to get under my skin with all these mods!! I go and do the one thing no one else has, and now I'm an outcast!!!!! ;D

Seriously though guys, thankyou very much for all your comments and advise. This is exactly what I need to hear. Constructive and informative abuse!!!! Will keep everyone updated, Its p**sing down here at the moment so no test ride!!
 

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Re: Kleen air system removal - Pic heavy!

This is the kind of thing that is constructive And What these forums are all about.
But get this The plot thickens. The port on top of the valve cover dose NOT go into the crankcase.

I had my exhaust valves out and was looking inside the exhaust port . I was surprised to see two holes. I sprayed brake clean into the hole and it comes out the top . Through the valve cover to a set of reeds valves that only allow air to enter the exhaust port and not allow exhaust gas to go into the clean air valve.

I thought the top was an air inlet for the crankcase but it is an air inlet for the exhaust it allows air to enter the exhaust to mix with any unburned fuel .Before going to the cat.I guess it is OK to plug the top port if you have a full exhaust system

The hole makes a little bump that I may have to weld closed for porting of the head.
 
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