Yamaha MBK X-MAX 300 2017, Service Manual

Page: 228 / 462

CYLINDER AND PISTON
5-33
EAS30289
REMOVING THE PISTON
1. Remove:
• Piston pin clips “1”
• Piston pin “2”
• Piston “3”
NOTICE
ECA13810
Do not use a hammer to drive the piston pin
out.
TIP
• Before removing the piston pin clips, cover the
crankcase opening with a clean rag to prevent
them from falling into the crankcase.
• Before removing the piston pin, deburr the pis-
ton pin clip groove and the piston pin bore ar-
ea. If both areas are deburred and the piston
pin is still difficult to remove, remove it with the
piston pin puller set “4”.
2. Remove:
• Top ring
• 2nd ring
• Oil ring
TIP
When removing a piston ring, open the end gap
with your fingers and lift the other side of the ring
over the piston crown.
EAS30291
CHECKING THE CYLINDER AND PISTON
1. Check:
• Piston wall
• Cylinder wall
Vertical scratches
→
Replace the cylinder,
piston, and piston rings as a set.
2. Measure:
• Piston-to-cylinder clearance
a. Measure cylinder bore “D” with the cylin-
der bore gauge.
TIP
Measure cylinder bore “D” between the intake
and exhaust sides of the cylinder.
b. If out of specification, replace the cylinder,
piston, and piston rings as a set.
c. Measure piston skirt diameter D “a” with
the micrometer.
Piston pin puller set
90890-01304
Piston pin puller
YU-01304
1
2
3
Bore
70.000–70.025 mm (2.7559–
2.7569 in)
a. 40 mm (1.57 in) from the top of the cylinder
b. Intake side
c. Exhoust side
D
a
b
c