Difference between 2 stroke and 4 stroke Engine

 In the 2 stroke engine it consists of one cycle
with one rotation
 In the 4 stroke engine it consists of one cycle
with two rotations.

 The inlet and the exhaust valves of the 4  stroke engine are replaced by 3 ports in a 2  stroke engine.
 In 2 stroke engine the lubrication oil must be
mixed with the petrol
 In case of 4 stroke engine the lubrication and  the fueling must take place separately
 In the 2 stroke engine due to the presence of  the lubrication oil, some of the lubrication oil  must be combusted during the time of heat  addition. Hence there is more friction and loss  of work in 2 Engine

 The power available in the 2 stroke engine is
only 70% of the calculated power
 In 4 stroke engine the power available is 90%
of the calculated power
 In 2 stroke engine the transfer port and the  exhaust port are opened at the same time.  Hence some fresh air fuel mixture will be  escaped out of the engine cylinder, due to  which there is loss of fuel.
 For single cylinder engine the size of the  flywheel is bigger than the 4 stroke engine.
 Due to the above reason the 2 stroke engine  on the roads are replaced by the 4 stroke  engine
 The overall efficiency of a 4 stroke engine is  much higher than that of a 2 stroke engine.