| 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. |