Piston Port?

Will someone give me a good explanation of how a piston port motor works compared to crankcase induction. i cant find one good explanation on the internet. i cant figure out how the crank gets lubricated...................thanks
 
the fuel mixture still goes to the crankcase first. when piston goes to tdc it creates a vacuum in bottom of case,piston then opens the intake port on cylinder and mixture gets sucked into case.on it's way to bdc piston closes intake port and pushes mixture thru the transfers.
just like a reed motor but the piston motion times the events by opening or closing the intake port.
simplified version.
 
Top Bottom