Yes, I called it a gearbox (a transmission) there is no such thing as venting a crankcase on a 2stroke, it relies on its sealing for building compression. The port induction of the distant past had the piston block the intake while it was going down, the reeds are a form of a one way valve, and the rotaries had the crankcase venting at part of the stroke and then shutting the rest of the 2 strokes through a rotating disk going past a window.
The gear boxes on 2 strokes are isolated from the crank, unlike modern 4stroke motorcycles which use the same oil in crankcase and gearbox. Although on some of them when main crankseals go (depending on the arrangement) compressed air escapes to the gear box, sometimes pumping the oil out of it. They usually don't run well enough or long enough to cause tranny damage. On some water cooled the oil is separated from the water side of the pump by a bearing and seal system. When that goes bad the bearing goes bad as well and steam/coolant pumps into the tranny. Which is one reason mostly 2 stroke street bikes will have that vent pointing away from the rear tire, for obvious reasons.