Checking The Piston Pin; Installing The Piston And Cylinder - Yamaha XT660Z 2008 Service Manual

3. Measure:
• Piston ring end gap
Out of specification → Replace the piston ring.
NOTE:
The oil ring expander spacer's end gap cannot
be measured. If the oil ring rail's gap is exces-
sive, replace all three piston rings.
Piston ring end gap
Top ring
0.20-0.35 mm
(0.0079-0.0138 in)
<Limit>: 0.60 mm (0.0236 in)
2 nd ring
0.35-0.50 mm
(0.0138-0.0197 in)
<Limit>: 0.85 mm (0.0335 in)
Oil ring
0.20-0.70 mm
(0.0079-0.0276 in)
EAS00265

CHECKING THE PISTON PIN

1. Check:
• Piston pin
Blue discoloration/grooves → Replace the
piston pin, and then check the lubrication
system.
2. Measure:
• Piston pin outside diameter "a"
Out of specification → Replace the piston
pin.
Piston pin outside diameter
22.991-23.000 mm
(0.9052-0.9055 in)
<Limit>: 22.971 mm (0.9044 in)
3. Measure:
• Piston pin bore inside diameter "b"
Out of specification → Replace the 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 inside diameter "b" –
Piston pin outside diameter "a"
EAS00267
INSTALLING THE PISTON AND
CYLINDER
1. Install:
• Top ring "1"
• 2 nd ring "2"
• Oil ring expander "3"
• Lower oil ring rail "4"
• Upper oil ring rail "5"
NOTE:
Be sure to install the piston rings so that the
manufacturer's marks or numbers face up.
a
5-29
CYLINDER AND PISTON
Piston pin bore inside diameter
23.004-23.015 mm
(0.9057-0.9061 in)
<Limit>: 23.045 mm (0.9073 in)
Piston-pin-to-piston clearance
0.004-0.024 mm
(0.0002-0.0009 in)
<Limit>: 0.074 mm (0.0029 in)