Checking The Air Induction System - Yamaha Vmax VMX17C 2009 Service Manual

EAS27060

CHECKING THE AIR INDUCTION SYSTEM

Air induction
The air induction system burns 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, allow-
ing secondary air to flow into the exhaust port.
The required temperature for burning the un-
burned exhaust gases is approximately 600 to
700 °C (1112 to 1292 °F).
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 when the coolant temperature is below
the specified value to allow the air to flow into the
exhaust pipe assembly. When the engine is
warm, the air cut-off valve opens while the vehi-
cle is decelerating if the throttle grip is in the fully
close position.
A
B
A
B
A. From the air filter case
B. To the cylinder head
1. Check:
• Hoses
Loose connections → Connect properly.
Cracks/damage → Replace.
2. Check:
• Reed valve
AIR INDUCTION SYSTEM
• Reed valve stopper
• Reed valve seat
Cracks/damage → Replace the reed valve
assembly.
3. Check:
• Air cut-off valve
Cracks/damage → Replace.
4. Check:
• Air induction system solenoid
Refer to "CHECKING THE AIR INDUCTION
SYSTEM SOLENOID" on page 8-138.
B
B
7-23