i'm not familiar with CZ motors but i assume this is what your working on.
with my Yammy motors i place the crank assembly in the freezer, which cools and shrinks it,
and i place the cases in the oven on around 100 celcius, which expands it.
{do a trial run first before placing either part in the oven or freezer to help eliminate any problems that may arise}
use gloves, it helps.
then quickly drop the crank into the case and whalah!
job done.