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A three-port engine refers to a traditional design found in two-stroke engines. It includes three primary ports that facilitate the intake, transfer, and exhaust processes within the engine. Here’s a breakdown of each port:

  1. Intake Port: This port connects the crankcase of the engine to the atmosphere. During the intake stroke, the downward movement of the piston creates suction in the crankcase, drawing in a fresh air-fuel mixture through the intake port. This mixture then fills the crankcase, ready for transfer to the combustion chamber.
  2. Transfer Port: The transfer port connects the crankcase to the combustion chamber. As the piston rises during the compression stroke, it compresses the air-fuel mixture in the crankcase. Near the top of the stroke, the transfer port opens, allowing the pressurized mixture to flow from the crankcase into the combustion chamber.
  3. Exhaust Port: The exhaust port provides a passage for the evacuation of spent exhaust gases from the combustion chamber. After combustion occurs, the piston begins its upward stroke, pushing the exhaust gases out through the exhaust port and into the exhaust system.

These three ports work together in a coordinated manner to facilitate the intake, compression, combustion, and exhaust processes in the engine. While the term “three-port engine” is commonly used, it’s worth noting that variations exist, and some engines may feature additional ports or different configurations depending on their specific design and application.

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