Toro 51603 Maintenance And Repair Manual page 5

GENERAL INFORMATION
The e e x p a n d i n g banding gases from the burning fuel in the
combustion chamber force the piston down the
cylinder, closing the third-port and increasing the
pressure
in
the crankcase. At a point approaching
the bottom of the stroke, the exhaust port opens and
the burnt gases begin to be expelled from the com-
bustion chamber (Fig. 4).
Mixture Compressed
Cl o sed
Figure 4
Power/Exhaust
At a point of piston travel slightly before bottom dead
center
(BBDC) the fuel transfer ports, on the sides c
the
cylinder walls, are uncovered and the com-
pressed fuel/air mixture in the crankcase is allowed
to
enter
the combustion chamber where they help
expel the burnt gases and charge the chamber fa
the following piston stroke (Fig.
5).
Figure
5
Exhaust/Fuel transfer