Checking The Piston Pin; Checking The Timing Chain Guide (Exhaust Side); Installing The Piston And Cylinder - Yamaha MBK X-MAX 300 2017 Service Manual

Piston ring
Top ring
End gap limit
0.50 mm (0.0197 in)
2nd ring
End gap limit
1.15 mm (0.0453 in)
EAS30293

CHECKING THE PISTON PIN

1. Check:
• Piston pin
Blue discoloration/grooves → Replace the
piston pin, and then check the lubrication sys-
tem.
2. Measure:
• Piston pin outside diameter "a"
Out of specification → Replace the piston pin.
Piston pin outside diameter
15.995–16.000 mm (0.6297–
0.6299 in)
Limit
15.975 mm (0.6289 in)
3. Measure:
• Piston pin bore diameter "b"
Out of specification → Replace the piston.
Piston pin bore inside diameter
16.002–16.013 mm (0.6300–
0.6304 in)
Limit
16.043 mm (0.6316 in)
CYLINDER AND PISTON
4. Calculate:
• Piston-pin-to-piston-pin-bore clearance
Out of specification → Replace the piston pin
and piston as a set.
Piston-pin-to-piston-pin-bore clearance =
Piston pin bore diameter "b" -
Piston pin outside diameter "a"
Piston-pin-to-piston-pin-bore
clearance
0.002–0.018 mm (0.0001–0.0007
in)
EAS30290
CHECKING THE TIMING CHAIN GUIDE
(EXHAUST SIDE)
1. Check:
• Timing chain guide (exhaust side)
Damage/wear → Replace.
EAS30294

INSTALLING THE PISTON AND CYLINDER

1. Install:
• Lower oil ring rail "1"
• Oil ring expander "2"
• Upper oil ring rail "3"
• 2nd ring "4"
• Top ring "5"
TIP
Be sure to install the piston rings so that the
manufacturer marks face up.
2. Install:
• Piston "1"
• Piston pin "2"
• Piston pin clips "3"
TIP
• Apply engine oil to the piston pin and connect-
ing rod.
• Make sure the punch mark "a" on the piston
points towards the exhaust side of the cylinder.
• Before installing the piston pin clips, cover the
crankcase opening with a clean rag to prevent
the clips from falling into the crankcase.
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