Air Induction System; Air Injection; Air Cut Off Valve - Yamaha XVZ13TF 1999 Service Manual

VIEW 1. (NO FLOW)
VIEW 2. (FLOW)

AIR INDUCTION SYSTEM

EB601000
AIR INDUCTION SYSTEM(AIS)

AIR INJECTION

This system burns the unburned exhaust gases
by injecting fresh air (secondary air) at the ex-
haust port. This is to reduce the output of the hy-
drocarbons.
When there is negative pressure around the ex-
haust port, the reed valve opens and the sec-
ondary air flows into the exhaust port.
The required temperature for burning the un-
burned exhaust gases is approximately 600_ to
700_C.
AIR CUT-OFF VALVE
The air cut-off valve is operated by intake gas
pressure through the diaphragm. Normally, this
valve is opened in order to allow fresh air to flow
into the exhaust port.
When the throttle is rapidly closed, negative
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.
VIEW 2. (FLOW)
During normal operation the valve is open.
A From the air filter
B To the reed valve
C To the carburetor joint
6-16
CARB