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:

    Checking the engine oil level
    1. Stand the vehicle on a level surface. NOTE: Place the vehicle on a suitable stand. Make sure the vehicle is upright. 2. Start the engine, warm it up for several minutes, and then turn it off. 3. Check: Engine oil level The engine oil level should be between the minimum level ...

    Installing the primary drive gear and balancer gears
    1. Install: Balancer driven gear "1" Lock washer Balancer drive gear "2" Primary drive gear Washer "3" Balancer driven gear nut Primary drive gear nut NOTE: Align the punch mark "a" in the balancer drive gear "2" with the punch mark "b" in the balancer driven gear "1". ...

    Installing the fuel hose
    1. Install: Fuel hose Fuel hose connector cover CAUTION:When installing the fuel hose, make sure that it is securely connected, and that the fuel hose connector cover is in the correct position, otherwise the fuel hose will not be properly installed. NOTE: W ...

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