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:

    Installing the shift forks and shift drum assembly
    1. Install: Shift fork-L "1" Shift fork-C "2" Shift fork-R "3" Shift drum assembly "4" Springs Shift fork guide bar "5" NOTE: The embossed marks on the shift forks should face towards the right side of the engine and be in the following sequence: "R", "C", "L". 2. Check: Tr ...

    Removing the handlebars
    1. Stand the vehicle on a level surface. WARNINGSecurely support the vehicle so that there is no danger of it falling over. 2. Remove: Handlebar grip "1" NOTE: Blow compressed air between the handlebar and the handlebar grip, and gradually push the grip off the handleb ...

    Checking the rear wheel
    1. Check: Rear wheel axle Rear wheel Wheel bearings Oil seals Refer to "CHECKING THE FRONT WHEEL" on page 4-8. 2. Check: Tire Rear wheel Damage/wear → Replace. Refer to "CHECKING THE TIRES" on page 3-23 and "CHECKING THE WHEELS" on page 3-25. 3. Measure: Radi ...

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