Yamaha YZF-R125 Service Manual: Air induction system

1. Air induction system hose (air filter case to reed valve assembly) 2. Air induction system reed valve assembly

3. Air induction system hose (reed valve assembly to exhaust pipe)

Checking the air induction system

Air injection

The air induction system burns unburned exhaust 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 (1112 to 1292 F).

1. Check:

• Hoses Loose connections Connect
  properly.

  Cracks/damage Replace.



• Cracks/damage  Replace.

2. Check:

• Air induction system reed valve assembly operation

a. Blow air into the pipe "1" of the air induction system reed valve assembly and check that it comes out from the pipe "2".

b. Blow air into the pipe "2" of the air induction system reed valve assembly and check that it does not come out from the pipe "1".

c. If faulty, replace the air induction system reed valve assembly.