Crank case venting with out air box??

I’d like to know what some of you are doing with the venting of your crankcase after you’ve remove the air box. I know people are sometimes using those small K&N type filters. I tried that and it worked but made a mess. I’m thinking about trying to hook that small filter to a long enough hose and mount it in between my pod filter in hopes that some of that oily crank case gases get sucked back into engine and burned off like they are supposed to. Anyone come up with some good way of handling this?

I connected a long hose and routed to the back just pass the mid way point of the swing arm. That way no oil gets sprayed on the bike. Ideally a catch box of some sort would be better but I don't care enough to build it.:blush:

I've got a K&N filter on the end of about 13 inches of hose anchored to the plastic molding in front of the battery tray under the seat. The hose runs basically straight up (with just a little bit of a backward angle, plus it sits above the pods and doesn't interfere at all with airflow)and I just drilled a hole for the mounting stud of the filter to anchor through the plastic. Works great and no mess.

I'm glad I saw this before posting a new thread - I took my rebuild project for its first ride yesterday and lost some oil out of the breather filter. I'm thinking the long hose and high-mounted filter might take care of that. Have to give it a try...

Why is it that some bikes can go with just a little filter and not blow any oil? Does a high performance engine create more blow-by? My entire engine is brand new so I didn't think I'd be blowing oil out of the breather.

Just noticed the "toonces" avatar!! LOL!!! I forgot all about that old SNL skit!:laugh:

"Why is it that some bikes can go with just a little filter and not blow any oil? "

Good question!!! Before I did the mods on my kz650 I ran with just a filter and never had any mess or problems. After installing the bigger carbs and better flowing pods (K&N instead of Emgo) I had to elevate the filter to keep oil off my crankcase. Not sure why that is either.

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I did the racer's choice...
I had to use a short vent plate on the supercharged unit... ran a hose to the under seat area... and added a catch bottle.

Along with the case vent, I vented the oil fill cap and ran a similar hose to the same catch bottle.

The bottle will emit vapors and under load, may produce a small amount of liquid... probably the vapor reformatting. I do not like the thought of ANY oil under the bike or near the tire.

Additionally -
THIS LINKS shows the oil fill cap vent

I've been wonderin about this too cause I don't want my freshly bead blasted engine a mess.

Has anyone ever played with an Exhaust crankcase evacuation system? You should be able to get suction from the exhaust if you have the proper venturi tube welded into the exhaust.

Introducing a vacuum into the crankcase is also supposed to give a little more power also by sealing up the rings tighter.

My engine is in good shape for original. I am running the small filter without the hose. No oil. I don't ride hard or launch and do wheelies. Yeah some bikes can run the small one.


--Sometimes I tell people they drive like toonces. If they don't know who that is it's ok. Toonces the driving cat.

I can't believe I'm leaking oil from this hole (see below). I think it's dripping from my breather filter into the motor mount area - would it come out here?? This is the hole opposite where the ground wire bolts into the cases. I've never seen oil come out of there...:blink:

Here's the current breather set up: