Yamaha YZF-R125 Service Manual: Checking the cylinder head
1. Eliminate:
- Combustion chamber carbon deposits (with a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid damaging or scratching:
- Spark plug bore threads
- Valve seats
2. Check:
- Cylinder head
Damage/scratches
Replace. - Cylinder head water jacket
Mineral deposits/rust
Eliminate.
3. Measure:
- Cylinder head warpage
Out of specification
Resurface
the cylinder head.
a. Place a straightedge "1" and a thickness gauge "2" across the cylinder head.
b. Measure the warpage.
c. If the limit is exceeded, resurface the cylinder head as follows.
d. Place a 400-600 grit wet sandpaper on the surface plate and resurface the cylinder head using a figure-eight sanding pattern.
NOTE:
To ensure an even surface, rotate the cylinder head several times.
Removing the cylinder head
1. Align:
"I" mark "a" on the generator rotor
(with the stationary pointer "b" on the generator
cover)
a. Turn the crankshaft counterclockwise.
b. When the piston is at TDC on the compre ...
Checking the camshaft sprocket and timing chain guide
1. Check:
Camshaft sprocket
More than 1/4 tooth wear "a" Replace
the
camshaft sprocket, timing chain and crankshaft
as a set.
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. C ...
Other materials:
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 ...
Installing the front brake master cylinder
1. Install:
Brake master cylinder "1"
Brake master cylinder holder "2"
NOTE:
Install the brake master cylinder holder with the
arrow mark "a" pointing forward.
Align the end of the brake master cylinder holder
with the punch mark "b" on the handlebar.
First, tighten the front bo ...
Adjusting the rear disc brake
1. Check:
Brake pedal position
(distance "a" from the center of the rider footrest
to the center of the brake pedal)
Out of specification Adjust.
2. Adjust:
Brake pedal position
a. Loosen the locknut "1".
b. Remove the cotter pin "2", washer "3", and
pin "4".
c. Turn t ...