Yamaha 2002 XJR1300 Service Manual - Page 31

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VIEW 1. (NO FLOW)

VIEW 2. (FLOW)

CARBURETOR

EAS00507

AIR INDUCTION SYSTEM

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

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.

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 cleaner

B To the cylinder

C To the carburetor joint

CARB