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Discussion Starter · #1 ·
All;

I warned ya..........stupid question time :)
1980 KZ750 G1......Breather box on top of the engine case. Has what looks like a barbed hose fitting coming out of the top. I just finished reading the removal and replacement procedure in the manual and answered the question I was going to submit.....Now I have a new one :-( The bike has had it's orginal airbox removed and has 2 what look like K+N filter units on the carbs. Is there a good way of routing a breather hose from the breather box into these K+N units??? Or am I going to have to srounge up the original box and put back stock?? I suspect that the vaccum produced by the orginal airbox vent assisted in lowering internal crankcase pressure, and by not having this I could possibly cause seepage of oil??? ( which I have by the way,,,cylinder to case flange R/S ) I get a bit of smoke/vapor from this box and when I ride to work at Oh Dark Thirty it's bit disconcerting to see smoke swirl around your headlight beam when stopped at at stopllight :-(
I'm open to any and all suggestions.
 

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GHOSTRIDER
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3,361 Posts
Most guys including myself, install a small breather filter into the crankcase breather opening where the tube once connected. I used a $12 stainless steel valve cover breather purchased at Autozone. I simply removed and inverted the rubber grommet in the cone shaped filter and it fit into the crankcase breather opening perfectly! It matched the pod intakes too! You can see it close up in pics of my bike in the "post pics" section under "Zoros Stallion" PS, there is no such thing as a stupid question, only stupid answers!
 

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retro rider
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If you over fill the oil you will get excess out the breather. Even not over filled my 900 makes a oily mess from oil/vapors coming out the breather.

As far as smoke - this is normal. You will get more smoke when the oil is fresh as the lower volatile components in the oil burn off. This smoke is routed back thru the engine on a stock air box. One of the disavantages of removing the stock air box - smell of the crank case blow-by..
 

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My KZ550A2 has the original airbox with the "PVC" (positive crankcase ventilation) intact. However, for many of my bikes, I just route this breather hose to the lower run of the drive chain and let a little oil mist keep my chain lubed. Probably a lot of the smoke is blow-by, but some is actually an aerosol of lube oil "fog". Sometmes engine oils are lacking in the antifoam performance, an attribute especialy required in high speed engines with integral gearboxes stirring the 'ell out of the oil, like the Kawasaki.
 

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GHOSTRIDER
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3,361 Posts
I did the same thing with my bike. I bought a stainless mesh breather from O'reilly Auto Parts
Yeah! Thats probably the most expensive looking least expensive mod/upgrade Ive made to the bike!:wink: Cool arent they, and they work wonderfully! And to comment on the previous posts; I personally Love the sights,sounds,and smells associated with internal combustion marvals! And my 30yr old v-twin destroying Kawasaki legend is entitled to a little smoke after she rolls to a stop after a good hard ride:sgrin: "thats when I grab a smoke too" :eek: Its normal for older looser......"Bikes!"
 

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Obsessed by Z1's
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When the engine runs, there is a small amount of exhaust gases that make it past the piston rings. This creates positive crankcase pressure that has to be vented to the outside. The higher the compressor, and the more worn the engine, the more gases flow out of the breather area.

As you have an oil mist on the inside of the engine, some of the oil comes out the breather too... certainly if you overfill the oil in the engine, the problem is much worse.

NEVER block the breather... if you do, the pressure inside the engine builds and forces oil past gaskets in all conceivable places...
 

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so when you have alittle oil in the stock air box its normal? If there is a lot of oil...... bad rings and/or too much oil?

I just happend to find alitlle in my air box and i got worried :eek: ..... so how much oil is too much in the air box?
 

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Last summer I was proud to run one of my older bikes that has something of an oil consumption problem. After about 200-300 miles of normal riding, I'd wring its neck for all of second gear and lay down a dramatic military quality smoke screen by blowing out the combustion chamber and exhaust system. Useful treatment for tailgaters. So, with the right attitude, a smoker can be quite beneficial and entertaining.
 
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