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Discussion Starter #1
1981 KZ550A2. Hey guys. In my overhaul of this engine I was surprised that the space under the breather cover atop the gearbox was just empty. As in the attached photo. I was expecting some kind of filter or mesh that would coalesce oil mist so that the liquid oil would drain back into the crankcase. Babbits parts diagram shows nothing in that space either. There is a small hole at about 7 o'clock for drainage and I guess vapors. Is this the ways it really is supposed to be? Thanks.
 

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It looks to me much like the set up on the older, bigger 4'(z1's,Kz900's,Kz1000's and Kz and GPz1100's). A short hose with a "S" bend connects to the air filter box on stock engines. The oil vapor is sucked into the engine reducing emissions.

I suppose a hose exiting to atmosphere would work, but might raise some eyebrows if your area requires testing for emissions.
 

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Discussion Starter #4
Mike:

There is a hose, straight shot of a few inches to the bottom of the airbox. I think all blowby gets into the intake air just like an automotive PVC system. Blowby is chemically reactive stuff and I hate to feed it to these precision carbs, so maybe I will use a draft tube like my Dad's old cars had. Bad boy that I am.
 

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I'd plug the hose opening in the air box as this wil be unfiltered air going to the carbs. Maybe a bolt and washer set up would work for a plug.
 

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It's been running that way all these many years w/o messing up the carbs so what makes you think it will mess them up to leave it the way it was designed?
 

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Z1...

sells a neat little filter just for that application.......of course I am too cheap to buy one and just put a length of rubber tubing on the nipple.....chris3
 

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I believe the "little filter" you speak of is the one designed to put on the crankcase vent if you are running pod filters and don't have an airbox.
 

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Discussion Starter #9
Thanks guys. This bike has 31000 km on it so not much blowby has hit the carbs. I ride about 20000 km per year, so in a couple of years these carbs will see more ugly gases than in their lifetime to date. I used to run field trials for lubricant testing in Montreal taxi cabs and dynamomter test cells. Feeding blowby back into the intake system is bad for deposits and engine wear. These blowby gases are very oxidatively corrosive. Even worse for the lungs, which is why they go back into the engine by legislation.
 
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