Disadvantages of two stroke engine:
The following are some of the disadvantages of two stroke engine when compared with four stroke engine:
1. As firing takes place in every revolution, time offered for cooling will be less than in a four stroke engine.
2. Incomplete scavenging results in mixing of exhaust gases with the fresh charge which will dilute it, hence less power output is obtained.
3. Since transfer port is kept open during a short period, less quantity of charge will be admitted into cylinder which will decrease power output.
4. Since both exhaust and transfer ports are kept open during same period, there is a possibility of escaping of the fresh charge through the exhaust port which will reduce the thermal efficiency.
5. For a given stroke and clearance volume, effective compression stroke is less in two stroke engine than in a four stroke engine.
6. In crankcase compressed type of 2 stroke engine, the volume of charge down into crankcase is less due to the reduction in the crankcase volume because of rotating parts.
7. A fan scavenged two stroke engine are having less mechanical efficiency as some power is required to run the scavenged fan.
8. A two stroke engine needs better cooling arrangement due to high operating temperature.
9. A two stroke engine consumes more lubricating oil.
10. The exhaust in two stroke engine is noisy because of sudden release of the burnt gases.