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:

    Cable routing
    Front brake light switch lead Right handlebar switch lead Throttle cable Main switch Clutch cable Clutch switch lead Left handlebar switch lead Sub-wire harness Horn Speed sensor lead Front brake hose Main switch lead Left headlight assembly lead Right headlight asse ...

    Unstable handling
    Handlebars - Bent or improperly installed right handlebar - Bent or improperly installed left handlebar 1. Steering head components - Improperly installed upper bracket - Improperly installed lower bracket (improperly tightened ring nut) - Bent steering stem - Damaged ball bearing or bearing ...

    Owner's tool kit
    Owner's tool kit Owner's tool kit Engine oil drain attachment The owner's tool kit is located under the rider seat. The service information included in this manual and the tools provided in the owner's tool kit are intended to assist you in the performance of preventive maint ...

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