Rear Of Engine Case...What is it?

Ok, guys it has been a while since I have messed with an old bike. When I bought my KZ1000 there were a few things missing in action.
What is the round area extruding from the rear of the engine behind the crank case?
There is a inlet or outlet area for a hose that must have ran to the air cleaner inwich is also MIA.
If I run single style foam air filters how would I incoroporate this?

You've got a couple choices anyway.
I just installed a K&N filter on my air breather,but I've heard of others just routing a hose,and hanging it out over the rear,at the swingarm frame axle-point.

I think Jeff sells those filters @ Z1,but not positive.

I've also heard that hanging it out the back could allow grits and grimes to enter the hose,but I don't know that that would be an issue or not.

Here...take a look at this(just found it)...


Air Filter

Thanks Sandy,
I figured it was the crank case breather hole, but wasn't for sure. Thanks for the help!

This works for me.

Larger clear hose is from crankcase oil breather.
Smaller clear hose is from drain hole at bottom of air box.

[click on image to enlarge -- and for legible text]

I picked me up a little breather from Advanced Auto Parts for $9. It is red with a chrome top and bottom, fits right on there.