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PORT TMING DIAGRAM FOR TWO STROKE CYCLE S.I ENGINE :

Two stroke cycle engines are provided with ports. The timing sequence of events like  opening and   closing of various ports are shown graphically in terms of crank angles from dead center positions. This diagram is known as port timing diagram. 

 The inlet port is opened by the piston 45* to 55* before TDC. The inlet port is closed by piston 45* to 55* after TDC position.

 The Exhaust port is opened by the piston 40* to 55* before BDC. The exhaust port is closed by the piston 40* to 55* after BDC position.

 The transfer port is opened by the piston 30* to 40* before BDC. The transfer port is closed by piston   30*  to 40* after BDC. Ignition occurs 15* to 20* before TDC.




 Port valve timing and Events during  Port timing 

 IPO - IPC   Air fuel Mixture is sucked into the crank case.

 IPC - TPO  Air fuel mixture is partially compressed in the crank case which is known as crank case   compression.

 TPO - TPC  Partially compressed air fuel mixture is transferred into the engine cylinder. 

 TPC - IG    Air fuel mixture is compressed in the cylinder. 

 IG              Air fuel mixture is ignited by the spark plug and burns. 

 IG - EPO   The burning Gases expand for doing work on the piston.

 EPO - EPC  Burnt gases are pushed out of the engine cylinder. 


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