Achieved by sucking induction in through the bore/piston wall ports, then on compression a read valve closes, sited after the carb, to prevent the gasses being forced back out, until the ports close as the piston rises. Then the real compression starts.
Crank bearing are part of the crank case induction chamber, as is the bore, so the inlet mix must be lubricated. Hence two stroke oil. Either by separate mechanical pump, or mixed with the petrol.
Exhaust is a dark art iirc. Hazey on this bit, but the key to it is timing, so the height of the exhaust port needs to be set so its revealed by the piston first for gasses to escape, but closes before the incoming petrol mix escapes.
Usual reason for common seizures is tuners getting greedy with port size and the piston ring escaping slightly in the port orifice, then trapping it by the rising piston.
Oily smelly unreliable things they are. So fazed out mostly. But they produce twice as much power as the four stroke, or the same amount for half the engine size, due to twice as many firing strokes.
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Topic: Two stroke cycle........Four stroke cycle (Read 1505 times)