Yamaha YZF-R125 Service Manual: Checking the piston rings

1. Measure:

Piston ring side clearance Out of specification Replace the
piston and piston rings as a set.

NOTE:

Before measuring the piston ring side clearance, eliminate any carbon deposits from the piston ring grooves and piston rings.


Checking the piston rings


2. Install:

  • Piston ring (into the cylinder)

NOTE:

Level the piston ring into the cylinder with the piston crown.

Checking the piston rings


a. 40 mm (1.57 in)

3. Measure:

  • Piston ring end gap Out of specification Replace
    the piston ring.

NOTE:

The oil ring expander spacer end gap cannot be measured. If the oil ring rail gap is excessive, replace all three piston rings.


    Checking the cylinder and piston
    1. Check: Piston wall Cylinder wall Vertical scratches Replace the cylinder, and replace the piston and piston rings as a set. 2. Measure: Piston-to-cylinder clearance a. Mea ...

    Checking the piston pin
    1. Check: Piston pin Blue discoloration/grooves  Replace the piston pin and then check the lubrication system. 2. Measure: Piston pin outside diameter "a" Out of specification ...

    Other materials:

    General tightening torque specifications
    This chart specifies tightening torques for standard fasteners with a standard ISO thread pitch. Tightening torque specifications for special components or assemblies are provided for each chapter of this manual. To avoid warpage, tighten multi-fastener assemblies in a crisscross pattern and ...

    Checking the transmission
    1. Measure: Main axle runout (with a centering device and dial gauge "1") Out of specification Replace the main axle. 2. Measure: Drive axle runout (with a centering device and dial gauge "1") Out of specification Replace the drive axle. 3. Check: Transmiss ...

    Checking the brake fluid level
    1. Stand the vehicle on a level surface. NOTE: Place the vehicle on a suitable stand. Make sure the vehicle is upright. 2. Check: Brake fluid level Below the minimum level mark "a" → Add the recommended brake fluid to the proper level. A. Front brake B. Rear brake WA ...

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