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Discussion Starter #1
Forgive my ignorance...this on-going debate is quite interesting...but what I'm hazy on is what creates the vacuum (that everybody wants to either block off or route to the crankcase)? What is in there actually creating suction? Mini-me with a Hoover?
 

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It works like a carb. The vacuum is created by the piston going down in the cylinder. Air is sucked through the reed valves into the exhuast manifold. This is to help burn fuel that escaped combustion.
 

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Not quite. The KLEEN system is their name for it ... everyone else calls it an "air injection" system.

Whenever there is an exhaust stroke, there is a strong pressure wave sent down the exhaust pipe that gets the column of air in the exhaust pipe moving, followed by a strong negative pressure wave when the exhaust stroke stops, and this happens in each of the four header pipes on every exhaust stroke. Within the cylinder head, there is a reed valve for each cylinder that only lets air IN during that negative pressure pulse. The extra air helps the catalyst burn off the nasty carbon monoxide and hydrocarbons. This system allows the engine to run slightly rich (for more power) without as much nasty stuff coming out the tailpipe.

I don't get why people disconnect this system. It doesn't cost any horsepower, it doesn't affect the way the engine runs, and it helps keep the air you breathe cleaner ...
 

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GoFaster said:
I don't get why people disconnect this system. It doesn't cost any horsepower, it doesn't affect the way the engine runs, and it helps keep the air you breathe cleaner ...
I did to make dyno tuning easier, and to seal the airbox.
 

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Discussion Starter #5
So I guess you have to suck it from the airbox and not just an open pipe because you don't want crap crudding up the reed valve?

If you hook this up to the crankcase then won't you be crudding up that reed valve with crankcase fumes?
 

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Kricket said:
So I guess you have to suck it from the airbox and not just an open pipe because you don't want crap crudding up the reed valve?

If you hook this up to the crankcase then won't you be crudding up that reed valve with crankcase fumes?
When the crankcase breather hose is connected to the airbox there is very little if any suction. The heated vapor from the engine migrates into the airbox from the pressure that builds up inside the engine. That hot vapor mixes with the fresh air, and gets drawn into the combustion chamber. The air suction system when hooked up draws from the same air, but the crankcase vapor is well diluted from the fresh air.
 

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Isnt hot air in your air box the last thing you want? I've always heard that cold air produces more hp, hence cold air intakes.
 

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Unless your engine has major leakdown, the amount of crankcase air being recirculated is insignificant. If your engine has major leakdown, then the best way to get the power back is to fix the source of the major leakdown!
 

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Frankyoz said:
Isnt hot air in your air box the last thing you want? I've always heard that cold air produces more hp, hence cold air intakes.
Exactly...... That's why I plan to seal all the holes into the airbox except the actual intake from the air filter. You then take the crankcase breather hose and put a filter on it, or directly on the crankcase breather port. This should be good for 1 to 3 hp do to cooler air. It's not much, but if you are like me everything counts. I plan to put a thin head gasket in. So the cooler the better. Maybe we should put chunks of dry ice in the airbox.:mrgreen:
 

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at -109 degrees F(or -78.5 deg. C) that would be nice, Except that it's solid carbon dioxide, and as a gas has 800 time the volume than the same weight as a solid. that wouldn't leave too much room for our friend, O2, me thinks. Anybody got any solid oxygen kickin' around? :) Oh wait, solid O2 is just cold nitrous without the N, Damn it! there goes my good idea for the day. Back to the 'coonass engineering' drawing table.
 

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gladding24 said:
Back to the 'coonass engineering' drawing table.
hey now!! Were's your RCA? :1848: I wanna see papers!

(Registered CoonAss-it's a Louisiana thing)
 

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SP8 BUSTED by Go Faster !!!!!

written by SP8

"It works like a carb. The vacuum is created by the piston going down in the cylinder. Air is sucked through the reed valves into the exhuast manifold. This is to help burn fuel that escaped combustion.




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

written by Go Faster

"Not quite. The KLEEN system is their name for it ... everyone else calls it an "air injection" system.

Whenever there is an exhaust stroke, there is a strong pressure wave sent down the exhaust pipe that gets the column of air in the exhaust pipe moving, followed by a strong negative pressure wave when the exhaust stroke stops, and this happens in each of the four header pipes on every exhaust stroke. Within the cylinder head, there is a reed valve for each cylinder that only lets air IN during that negative pressure pulse. The extra air helps the catalyst burn off the nasty carbon monoxide and hydrocarbons. This system allows the engine to run slightly rich (for more power) without as much nasty stuff coming out the tailpipe.

I don't get why people disconnect this system. It doesn't cost any horsepower, it doesn't affect the way the engine runs, and it helps keep the air you breathe cleaner ... "



from Tberd

There goes you credibility SP8 . You got OWNED !!!
 

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miykl said:
hey now!! Were's your RCA? :1848: I wanna see papers!

(Registered CoonAss-it's a Louisiana thing)
It's ummm, errrrr....in the mail.,,,...No, that's not it....uhhhhhh, ....it's on its way from the RCAESOE(Registered CoonAss Engineering Society Of Engineers), yeah, that's it.

(I grew up in Vermont, that ought to be close enough to CoonAss)
 

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Discussion Starter #14
SP8 said:
When the crankcase breather hose is connected to the airbox there is very little if any suction. The heated vapor from the engine migrates into the airbox from the pressure that builds up inside the engine. That hot vapor mixes with the fresh air, and gets drawn into the combustion chamber. The air suction system when hooked up draws from the same air, but the crankcase vapor is well diluted from the fresh air.
Yeah, I get all that, but why would you suck air from the airbox into the exhaust and not just have an open hose sticking out somewhere that sucks the air in?
 

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Kricket said:
Yeah, I get all that, but why would you suck air from the airbox into the exhaust and not just have an open hose sticking out somewhere that sucks the air in?
Oh I see what your saying. The air in the airbox is more consistent. The airbox takes out turbulence which will give you a nonconsistent flow of air.
 

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tberd said:
OMG !! LOL .
Ok.... Why don't you explain why. As far as I know the airbox is for filtering, noise reduction, and to stablize the air. In the case of ram air it gets pressurized.
 

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dnwhoop02 said:
maybe I should connect the crankcase breather hose to this discussion.... cause it sucks! :mrgreen:
or blows depending on your position. :bj: :lol:

BD
 

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Kricket said:
Yeah, I get all that, but why would you suck air from the airbox into the exhaust and not just have an open hose sticking out somewhere that sucks the air in?
Because you want to suck FILTERED air into the reed valves to avoid wearing them out with dust particles.

This discussion has gone into piecemeal discussions about bits and pieces of the system without looking at the whole picture.

The stock setup has a vent hose from the crankcase to the airbox so that the engine draws in and re-burns anything that leaks past the pistons. This is the "Crankcase Ventilation" system. That's all there is to it. No control valves no nothing. It is an emission-control system to stop hydrocarbons in those gases from going into the atmosphere.

The stock setup has a hose from the airbox to the solenoid valve that controls the air-suction (KLEEN) system. From the solenoid valve, hoses go to the reed valves that admit air into the exhaust ports. This is an emission-control system to give extra air to allow the catalyst to do its job. On older Kawasaki bikes, there was also a control valve, but it was vacuum operated. The air suction system is "ON" when the engine is under load, and it is "OFF" during coasting in order to reduce the amount of backfiring through the exhaust. With this one being electronically controlled, it can be "smarter" than the older systems that switched off when intake vacuum was more than a certain amount, but only a little bit, it is still only "on" or "off". On the older models, the vacuum that caused the air-suction valve to go "off" was more than what the engine pulls at idle. Hence, the ONLY time the air-suction system was switched off was when coasting down with closed throttle from higher engine speeds. At all other times, air is injected. At idle, at cruise, at full load. Always except during coastdown.

Yes, the air-suction valve is drawing in a mixture of fresh air and a wee tiny bit of recirculated crankcase fumes, but it's irrelevant, it's the same mixture of 99% air and 1% blowby that the engine itself is using.

OK, that's how the stock system works. Now, modifications.

Bypassing the KLEEN system by blocking off the ports - Good thing to do temporarily during dyno-testing to get an accurate air/fuel ratio reading. In fact, you had better disable KLEEN in order to do this. But why install block-off ports for this? No need. Just unplug the hose from the airbox and temporarily plug it and the hole into the airbox. Done deal - just as good. But ... In the interest of breathing clean air, re-connect the system afterward. It doesn't cost any horsepower.

Rearranging the KLEEN system to draw in crankcase fumes while blocking off the airbox connection that normally goes to the KLEEN - This should pull a slight vacuum on the crankcase. It might reduce pumping losses a teeny little bit. It has been pointed out that the recirculation gases are hot. They're not all THAT hot - they are going through a rubber hose. The volume of blowby compared to the volume of main air should be insignificant. If it isn't, you're better off fixing the cause of the blowby, because that's costing you more power than the slight temperature increase from the blowby gases. I have not seen a dyno test of whether this modification accomplishes anything in reality. It would increase exhaust emissions by interfering with the way the catalyst works.
 
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