| Two-stroke engine
|| Four-stroke engine
| Two-stroke engine has ports for inlet , outlet and transfer.
|| Four-stroke engine has two complicated valves , one for inlet and one for outlet .
| Two-stroke engine gives one power stroke in each revolution of the crank-shaft.
|| Four-stroke engine gives one power stroke in two revolutions of the crank-shaft.
| For same size, same speed and same running conditions two stroke engine developes twice the power developed by four-stroke engine.
|| Power developed by four-stroke engine for same size , same speed and same running conditions is almost half same running condition is almost half of the power developed by two-stroke engines.
| It provides simplicity as valves, rocker arms, push-rods ,cam and cam shafts are not required to operate ports.
|| Due to valves , rocker arms , push rods , cam and cam shafts construction is complicated and friction loss is also greater.
| High temperature is attended during the operation of two stroke engine hence more cooling is required.
|| Lower operating temperature in comparison to two-stroke engines. Less cooling is required.
| Two stroke engines are much easier to start.
|| Four stroke engines are difficult to start.
| The initial cost is considerably less.
|| The initial cost is considerably high.