Air Induction System (Ais) 5-1; Air Injection; Air Cut-Off Valve - Yamaha XVS650 Service Manual

AIR INDUCTION SYSTEM (AISI
ICARBIIiII
EB601000
AIR INDUCTION SYSTEM (AIS)
AIR INJECTION
This system burns the unburned exhaust
gases by injecting fresh air (secondary air)
at the exhaust port. This is to reduce the
output of the hydrocarbons.
When there is negative pressure around the
exhaust port, the reed valve opens and the
secondary air flows into the exhaust port.
The required temperature for burning the
unburned exhaust gases is approximately
600° to 700°C.
VIEW
2.
(FLOW)
During normal operation the valve is open.
lAl
From the air fiiter
[ID To the reed valve
To the carburetor joint
AIR CUT-OFF VALVE
The air cut-off valve is operated by intake
gas pressure through the diaphragm. Nor-
mally, this valve is opened in order to allow
fresh air to flow into the exhaust port.
When the throttle is rapidly closed, nega-
tive pressure is generated and the valve
closes in order to prevent after-burning.
VIEW 1. (NO FLOW)
When decelerating (the throttle closes), the
valve will close.
[ftI
VIEW 1. (NO FLOW)
VIEW 2. (FLOW)
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