Yamaha YZF-R125 Service Manual: Checking the cylinder and piston

Yamaha YZF-R125 Service Manual / Engine / Cylinder and piston / 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. Measure cylinder bore "C" with the cylinder bore gauge.

Checking the cylinder and piston

NOTE:

Measure cylinder bore "C" by taking side-to-side and front-to-back measurements of the cylinder.

Then, find the average of the measurements.

b. If out of specification, replace the cylinder, and replace the piston and piston rings as a set.

c. Measure piston skirt diameter D "a" with the micrometer.

Checking the cylinder and piston

b. 5.0 mm (0.20 in) from the bottom edge of the piston

d. If out of specification, replace the piston and piston rings as a set.

e. Calculate the piston-to-cylinder clearance with the following formula.

f. If out of specification, replace the cylinder, and replace the piston and piston rings as a set.

Removing the piston

1. Remove: Piston pin clips "1" Piston pin "2" Piston "3" CAUTION:Do not use a hammer to drive the piston pin out. NOTE: Before removing the piston pin c ...

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 ...

Other materials:

Checking the front brake disc
1. Remove: Front wheel Refer to "FRONT WHEEL" on page 4-6. 2. Check: Brake disc Damage/galling Replace. 3. Measure: Brake disc deflection Out of specification Correct the brake disc deflection or replace the brake disc. a. Place the vehicle on a suitable stand ...

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 ...

Checking the condition of the bulbs
The following procedure applies to all of the bulbs. 1. Remove: Bulb WARNINGSince the headlight bulbs get extremely hot, keep flammable products and your hands away from them until they have cooled down. CAUTION: Be sure to hold the socket firmly when re ...