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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