Air Induction System (Ais); Air Induction; Air Cut-Off Valve - Yamaha BT1100 2002 Service Manual

VIEW 1
VIEW 2

AIR INDUCTION SYSTEM (AIS)

EB601000
AIR INDUCTION SYSTEM (AIS)
AIR INDUTION
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 hydrocar-
bons.
When there is negative pressure around the ex-
haust port, the reed valve opens and the second-
ary air flows into the exhaust port.
The required temperature for burning the unburned
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 pres-
sure 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 cylinder heads
[C] To the carburetor joint
1 Reed valve
5-10
CARB