There's not a lot
This isn't mine, it's a picture I grabbed off the internet because I cba to go taking photos at this time of night... the relevant pipes are highlighted in groovy and psychedelic colours.
The green one is the "inlet", running from the air filter box to the top of the rocker cover. They don't all have it - the oil filler cap allows air in instead.
The purple one is the "outlet", connected to the manifold, using manifold depression to suck fumes out of the crankcase. The other end of it connects to a little tin box on the side of the block, which is a chamber to let suspended oil drop out of the airflow rather than being carried over into the intake. It has a restriction in it to stop it letting too much air through and ruining the idle mixture; IIRC this is the narrow bore of the connection to the manifold.
Bits that might get gunked up: that narrow bore, the tin box, the mesh inside the oil filler cap - ie, nothing that'll take any harm from being left to soak in a bucket of petrol.