TOPIC:

On the big fours there is a big drum with two tubes on an angle so the gasses will swirl causing the large particles of oil to condense and go back in the case. A lot of guys went to a low profile one like yours. I guess Kaw figured the drum wasn't needed. The vent should have a tube going to the air box or down to the chain.
Steve

I put a K&N breather filter into the cover-hole after reaming it out for the tube. It definitely ventilates hot oil vapor, and likely some internal engine pressure as well.

What would happen if that hole was plugged instead?

That's ill advised. The pressure must be able to escape. If not the pressure will start to get past the rings and heat will build up. The good thing about having it go to the airbox is the heat and pressure is taken out of the engine. If nothing else it should be routed down to the chain or out the back.
Steve

If you plug it up you the pressure may blow out through the seals around the crankshaft, shifter shaft, etc. Definitely not a good thing to do. Ed

I've always used a K and N filter too maybe 2 or 3 times that size (hooked to the stock tube) but have been "reamed" by a few members for it. For us pod users I suppose that or like Steve says simply a tube running to the back or the chain might be better. Like stated by the nay sayers it could be clogged up with blow by but mine has stayed pretty clean and I have only cleaned it a couple times. Looks nice and clean Daveo.

650ed wrote: If you plug it up you the pressure may blow out through the seals around the crankshaft, shifter shaft, etc. Definitely not a good thing to do. Ed

Figured that.
There must be significant pressures in there, judging by the steamy vapor and potent odor when the engine is hot. No fun idling at stop lights on a hot day with no breeze.

KZB2 650 wrote: I've always used a K and N filter too maybe 2 or 3 times that size (hooked to the stock tube) but have been "reamed" by a few members for it. For us pod users I suppose that or like Steve says simply a tube running to the back or the chain might be better. Like stated by the nay sayers it could be clogged up with blow by but mine has stayed pretty clean and I have only cleaned it a couple times. Looks nice and clean Daveo.

No chain, but the tube to the rear idea...no thanks

KZB2 650 wrote: I've always used a K and N filter too maybe 2 or 3 times that size (hooked to the stock tube) but have been "reamed" by a few members for it. For us pod users I suppose that or like Steve says simply a tube running to the back or the chain might be better. Like stated by the nay sayers it could be clogged up with blow by but mine has stayed pretty clean and I have only cleaned it a couple times. Looks nice and clean Daveo.

I have a piece of hosing attached to the hole and at the other end, a filter. The filter vents just above the swing arm.

That little breather filter lets vapors pass through really well.
Having the K&N breather-filter tube (friction-fit) inside the engine cover post directs any collected oil back into the motor. No oil has gotten through the filter so-far, at least none I can see.

If you have a cracked ringland and busted rings you can attach a hose and fog for mosquitoes.

MadShad wrote: If you have a cracked ringland and busted rings you can attach a hose and fog for mosquitoes.

I like it! You could run the hose to the front of the bike, and save a few bugs from a big flying object.

Am not a fan of attaching a filter on the crankcase breather or on the end of the breather tube.

Imo, the filter contributes nothing, and gets progressively clogged with oil, which diminishes breathing ability of the crankcase.

Oh Wait! The filter might prevent oil-eating alien beings from entering the crankcase.

And when feeling the inexplicable need to filter out-coming whatever from the engine, should definitely also add a filter to the end of each muffler.

Filters may also be added to the ends of handlebar grips, and to the ends of foot-pegs, and to the ends of valve stems to assure that any old unclean air that escapes from inside the handlebars or foot-pegs or from inside the tire through a leaking valve stem will be squeaky clean before entering the atmosphere.

Good Fortune!