KEEWAY 50cc Series Service Manual page 16

Now the piston is reaching TDC,
completely compressing the air/fuel mix in
the combustion chamber. NOTE: The
exhaust and transfer ports are still blocked
by the piston skirt; the intake port is still
open, but the crankcase has now filled to
capacity.
The spark plug now fires, igniting the
compressed mixture in the combustion
chamber.
Once the mix has been ignited, the
following explosion forces the piston
back down at a very high rate of speed.
This generates the power required to
perform the workload.
NOTE: All three ports are now closed.
As this downward motion occurs, the
air/fuel mixture in the crankcase is
compressed.
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