Actually, the air/fuel charge enters the crankcase under the piston, and, passes through the crankcase first, before it enters the combustion chamber, via the transfer ports. It is oiled from the mixture entering the crankcase first. In the Tomos reed valve engine, the charge enters both the crankcase and the cylinder, and is prevented from escaping back through the intake port by the reed shutting.
If you'll look, when the piston is near TDC, the "intake port" of the cylinder is opened and closed by the movement of the piston. The charge enters the crankcase underneath the piston, down the lower portion of the cylinder. As the piston is coming down, and the itake is shut-off, the mixture is then squeezed up through the transfer ports, on the top side of the piston, inside the combustion chamber.
Hope this helps.