Why not make it even simpler..
Remove the head.. Crank the engine over by some artificial means.. use the pedals?
Compression test: hmm.. Compression = zero PSI.
However, a vacuum was created in the crankcase and fuel was sucked into the crankcase and was forced through the transfer ports and, in this experiment, spewed into the open air.
compression in the combustion chamber, which is the type of compression we are discussing, has nothing to do with creating a vacuum in the crankcase..