Carburetors; Air Induction System; Air Injection; Air Cutoff Valve - Yamaha YZF-R1 2000 Supplementary Service Manual

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

AIR INDUCTION SYSTEM

EAS00507

CARBURETORS

AIR INDUCTION SYSTEM

AIR INJECTION

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, 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 CUTOFF VALVE

The air cutoff valve is operated by the intake gas
pressure through the piston valve diaphragm.
Normally, the air cutoff valve is open to allow
fresh air to flow into the exhaust port. During
sudden deceleration (the throttle valve sudden-
ly closes), negative pressure is generated and
the air cutoff valve is closed in order to prevent
after-burning.
Additionally, at high engine speeds and when
the pressure decreases, the air cutoff valve au-
tomatically closes to guard against a loss of per-
formance due to self-EGR.
(This "low-boost close" function is the same as
on the FZR600 (3HW).)
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
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CARB