Yamaha YZ125X 2022, Owner'S Service Manual

Page: 169 / 268

CYLINDER HEAD, CYLINDER AND PISTON
5-9
e. If out of specification, replace the piston
and piston rings as a set.
f. Calculate the piston-to-cylinder clearance
with the following formula.
g. If out of specification, replace the cylinder,
and replace the piston and piston rings as
a set.
EAM30547
COMBINATION OF PISTON AND CYLINDER
1. Check:
•
Cylinder mark “a”
2. Check:
•
Piston mark “a”
3. Combination:
•
Combine the piston and cylinder by the fol-
lowing chart.
TIP
When you purchase a cylinder, you cannot des-
ignate its size. Choose the piston that matches
the above chart.
Diameter
53.957–53.972 mm (2.1243–
2.1249 in)
a. 17.5 mm (0.69 in) from the bottom edge of
the piston
Piston-to-cylinder clearance =
Cylinder bore - Piston skirt diameter
Piston-to-cylinder clearance
0.040–0.045 mm (0.0016–0.0018
in)
Cylinder mark “a” Cylinder size
A
54.000–54.002 mm
(2.1260–2.1261 in)
B
54.004–54.006 mm
(2.1261–2.1262 in)
C
54.008–54.010 mm
(2.1263–2.1264 in)
D
54.012–54.014 mm
(2.1265–2.1265 in)
a
Piston mark “a”
(color)
Piston size
A (red)
53.957–53.960 mm
(2.1243–2.1244 in)
B (orange)
53.961–53.964 mm
(2.1244–2.1246 in)
C (green)
53.965–53.968 mm
(2.1246–2.1247 in)
D (purple)
53.969–53.972 mm
(2.1248–2.1249 in)
Cylinder mark Piston mark (color)
A A (red)
B B (orange)
C C (green)
D D (purple)