Yamaha 2009 VMX17YC, Service Manual

Page: 357 / 583

CONNECTING RODS AND PISTONS
5-84
2. Install:
• Piston ring
(into the cylinder)
TIP
Level the piston ring into the cylinder with the
piston crown.
3. Measure:
• Piston ring end gap
Out of specification
→
Replace the piston
ring.
TIP
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.
EAS24440
CHECKING THE PISTON PINS
The following procedure applies to all of the pis-
ton pins.
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.
3. Measure:
• Piston pin bore inside diameter “b”
Out of specification
→
Replace the piston.
Piston ring
Top ring
Ring side clearance
0.030–0.070 mm (0.0012–
0.0028 in)
Limit
0.120 mm (0.0047 in)
2nd ring
Ring side clearance
0.020–0.060 mm (0.0008–
0.0024 in)
Limit
0.120 mm (0.0047 in)
a. 9.8 mm (0.39 in)
Piston ring
Top ring
End gap (installed)
0.20–0.35 mm (0.0079–0.0138
in)
Limit
0.60 mm (0.0236 in)
2nd ring
End gap (installed)
0.40–0.55 mm (0.0157–0.0217
in)
Limit
0.80 mm (0.0315 in)
Oil ring
End gap (installed)
0.20–0.50 mm (0.0079–0.0197
in)
Piston pin outside diameter
18.991–19.000 mm (0.7477–
0.7480 in)
Limit
18.971 mm (0.7469 in)