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A two stroke engine can be identified by

A two stroke engine can be identified by Correct Answer Absence of valves

Explanation:

A two-stroke engine does not require valves because in two-stroke engine there are ports (transfer port and exhaust port) present in the engine cylinder.

Additional Information

Working of Two- Stroke Engine:

First Stroke (Suction and compression):

  • As the piston moves up from BDC towards TDC, it closes the inlet port, exhaust port and the transfer port.
  • Further upward movement of the piston results in compressing the mixture in the cylinder and opening of the inlet port.
  • The upward motion of the piston creates a partial vacuum inside the crankcase below the piston, and the air/fuel mixture is drawn into the crank-case through the inlet port.
  • The exhaust and transfer port remain closed during the operation of the upward stroke and the charge which reached above the piston during the previous stroke is compressed.

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Thus, suction and compression stroke takes place during the piston moves from BDC to TDC.

Second Stroke (power and exhaust): 

  • The piston is forced downward from the TDC. During this stroke, the exhaust port opens and burnt gases escape into the atmosphere.
  • Further downward movement of the piston opens the transfer port and allows the partially compressed mixture, received during the previous stroke, to reach the combustion chamber from the crankcase.
  • The piston head has a spherical shape. It deflects a fresh charge of fuel mixture up into the cylinder.
  • The mixture flows down and pushes the burnt gases out, through the exhaust port. This process is called scavenging.

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