SECTION 4
4-8
3-/ 4-Cylinder
DESCRIPTION OF OPERATION
The power head of this outboard motor is a two-
stroke engine (or two-stroke cycle engine). The engine completes
its one cycle operation including gas mixture suction, compression,
explosion and exhaust while the crankshaft rotates once i. e. the
piston moves upward and then downward (two strokes).
As the piston starts to move toward top dead center (TDC), the
interior of the crank case is made vacuum pressure causing the
reed valve to open and the gas mixture to be taken into the
crankcase. As the piston comes near the TDC, the spark plug
produces the sparks to ignite the compressed gas mixture for
combustion. As the fuel mixture is exploded, the piston moves
toward bottom dead center (BDC) and open the exhaust port and
then scavenging port. The scavenging is an action that sends the
fresh gas mixture in the crankcase to the cylinder.
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T1160 T1161
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