Yamaha 2002 TDM900, Service Manual

Page: 394 / 475

7-31
AIR INDUCTION SYSTEM
FI
EAS00507
AIR INDUCTION SYSTEM
AIR INJECTION
The air induction system bums unburned ex-
haust gases by injecting fresh air (secondary
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.
EAS00508
AIR CUT-OFF VALVE
The air cut-off valve is controlled by the signals
from the ECU in accordance with the combus-
tion conditions. Ordinarily, the air cut-off valve
opens to allow the air to flow during idle and
closes to cut-off the flow when the motorcycle is
being driven. However, if the coolant tempera-
ture is below the specified value, the air cut-off
valve remains open and allows the air to flow
into the exhaust pipe until the temperature be-
comes higher than the specified value.
A From the air filter case
B To the reed valve