Yamaha GT1 Service Manual page 21

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WHAT IS THE TORQUE INDUCTION-
Action of Piston in Torque Induction
4. Piston Opens Exhaust Port and then
Opens Transfer Port
Exhaust port is cleared and burned gases is pushed
out in a stream.
As piston lowers, fuel-air mixture in crankcase
begins to be compressed.
As piston moves down further, main auxiliary
transfer and 5th ports are cleared, and compressed
mixture in crankcase steams into cylinder. As a
result, crankcase pressure decreases.
5. Piston Opens Transfer Port add Moves
Down to 8. D.C.
Main and auxiliary transfer ports open, and fuel-
air mixture is induced into cylinder from crank-
case and forces burned gases out of cylinder,
thereby filling the cylinder.
As piston moves down further, main, auxiliary
transfer and 5th ports are cleared, and compressed
mixture in crankcase steams into cylinder. As a
result, crankcase pressure decreases.
e Scavenging by the 5th Port
On the 5-port cylinder, the auxiliary transfer ports
are positioned on the same level as the main
transfer ports. As the piston lowers to the
position as illustrated, the fuel-air mixture in the
cylinder is compressed and is going to steam into
the cylinder through the main and auxiliary
transfer ports. On the torque induction, too, the
compressed mixture is about to steam into the
cylinder through the inlet port of the piston.
As the piston moves down further, the main,
auxiliary and 5th ports are cleared and the fuel-air
mixture enters the cylinder in streams. In this
case, the inertia effect of the streams causes the
reed valve to open, and the fuel-air mixture passing
through the reed valve flows directly into the
cylinder through the 5th port (the mixture does
not enter the crankcase), thereby
burned gases out of the cylinder.
scavenging action of the 5th port.
forcing the
This is the
Fig. 3-2-4
Fig. 3-2-5
Fig. 3-2-6
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