Yamaha YZF-R125 Service Manual: Air induction system

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)

Air induction system


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".

Checking the air induction system


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

    Installing the throttle body
    1. Install: Throttle body joint clamps NOTE: Align the projections "a" on the throttle body joint with the slot "b" in each throttle body joint clamp. 2. Install: Throttle body joint ...

    Electrical system
    ...

    Other materials:

    Intake air temperature sensor
    1. Check: Intake air temperature sensor resistance Out of specification Replace the throttle body. a. Connect the pocket tester ( × 1k) to the throttle body sensor assembly coupler as shown. Positive tester probe brown/white "1" Negative tester probe gray/black ...

    Assembling the main axle and drive axle
    1. Install: Toothed washer "1" Circlip "2" NOTE: Be sure to install the circlip so that its sharp edge "a" is facing away from the toothed washer and gear. Be sure the circlip ends "b" are positioned at the axle spline groove "c". 2. Install: 2nd pinion gear "1" NO ...

    Installing the clutch
    1. Install: Conical spring washer "1" NOTE: Install the conical spring washer as shown in the illustration. 2. Install: Clutch housing Thrust washer "1" NOTE: Be sure to install the thrust washer so that its sharp edge "a" is facing away from the clutch boss. 3. Instal ...

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