Air Induction System; Air Injection; Air Cut-Off Valve - Yamaha XV1700P Service Manual

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AIR INDUCTION SYSTEM

EAS00507
AIR INDUCTION SYSTEM

AIR INJECTION

The air induction system burns unburned
exhaust gases by injecting fresh air (second-
ary air) into the exhaust port, reducing the
emission of hydrocarbons.
When there is negative pressure at the
exhaust port, the reed valve opens, allowing
secondary air to flow into the exhaust port. The
required temperature for burning the unburned
exhaust gases is approximately 600 to 700 °C
(1,112 to 1,292 °F).
EAS00508

AIR CUT-OFF VALVE

The air cut-off valve is operated by the intake
gas pressure through the piston valve dia-
phragm. Normally, the air cut-off valve is open
to allow fresh air to flow into the exhaust port.
During sudden deceleration (the throttle valve
suddenly closes), negative pressure is gener-
ated and the air cut-off valve is closed in order
to prevent after-burning.
Additionally, at high engine speeds and when
the pressure decreases, the air cut-off valve
automatically closes to guard against a loss of
performance due to self-EGR.
1 During normal operation, the air cut-off valve is
open.
2 During sudden deceleration (the throttle valve
É
suddenly closes), the air cut-off valve closes.
3 At high engine speeds and when the pressure
decreases, the air cut-off valve is closed.
È From the air cleaner
É From the reed valve
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