Removing The Piston; Checking The Cylinder And Piston - Yamaha MBK X-MAX 300 2017 Service Manual

EAS30289

REMOVING THE PISTON

1. Remove:
• Piston pin clips "1"
• Piston pin "2"
• Piston "3"
ECA13810
NOTICE
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".
Piston pin puller set
90890-01304
Piston pin puller
YU-01304
2. Remove:
• Top ring
• 2nd ring
• Oil ring
3
1
2
5-33
CYLINDER AND PISTON
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.
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
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.
b
a
D
c