Yamaha YZF-R125 Service Manual: Installing the valves

The following procedure applies to all of the valves and related components.

1. Deburr:

  • Valve stem end (with an oil stone)

Installing the valves


2. Lubricate:

  • Valve stem "1"
  • Valve stem seal "2"
    (with the recommended lubricant)

Installing the valves


3. Install:

  • Lower spring seat "1"
  • Valve stem seal "2"

  • Valve "3"
  • Valve spring "4"
  • Upper spring seat "5" (into the cylinder head)

NOTE:

  • Make sure each valve is installed in its original place.
  • Install the valve springs with the larger pitch "a" facing up.

Installing the valves


b. Smaller pitch

4. Install:

  • Valve cotters "1"

NOTE:

Install the valve cotters by compressing the valve spring with the valve spring compressor and the valve spring compressor attachment "2".


Installing the valves


5. To secure the valve cotters onto the valve stem, lightly tap the valve tip with a soft-face hammer.

CAUTION:

Hitting the valve tip with excessive force could damage the valve.

Installing the valves


    Checking the valve springs
    The following procedure applies to all of the valve springs. 1. Measure: Valve spring free length "a" Out of specification Replace the valve spring. 2. Measure: Compressed valve ...

    Cylinder and piston
    ...

    Other materials:

    Removing the front wheel (disc)
    1. Stand the vehicle on a level surface. WARNINGSecurely support the vehicle so that there is no danger of it falling over. 2. Elevate: Front wheel NOTE: Place the vehicle on a suitable stand so that the front wheel is elevated. 3. Remove: Front brake caliper NO ...

    Installing the drive chain
    1. Lubricate: Drive chain Master link 2. Install: Drive sprocket Drive sprocket retainer bolts 3. Install: Master link O-rings Master link plate Master link clip "1" CAUTION: The closed end of the master link clip must face in the direction of drive ch ...

    Periodic maintenance and adjustment
    Periodic inspection, adjustment, and lubrication will keep your vehicle in the safest and most efficient condition possible. Safety is an obligation of the vehicle owner/operator. The most important points of vehicle inspection, adjustment, and lubrication are explained on the followin ...

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