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 radiator
    1. Check: Radiator fins obstruction clean. Apply compressed air to the rear of the radiator. Damage  repair or replace. NOTE: Straighten any flattened fins with a thin, flat-head screwdriver. 2. Check: Radiator hoses Cracks/damage Replace. 3. Measure: Radiator cap ...

    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 ...

    Adjusting the front wheel static balance
    NOTE: After replacing the tire, wheel or both, the front wheel static balance should be adjusted. Adjust the front wheel static balance with the brake discs installed. 1. Remove: Balancing weight(s) 2. Find: Front wheel's heavy spot NOTE: Place the front wheel on a suitab ...

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