Yamaha FJR13AG, Service Manual

Page: 418 / 784

CONNECTING RODS AND PISTONS
5-89
2. Install:
• Piston ring
(into the cylinder)
TIP
Use the piston crown to level the piston ring near
bottom of cylinder “a”, where cylinder wear is
lowest.
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.
EAS30749
CHECKING THE PISTON PIN
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 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.
b. Top of cylinder
Piston ring
Top ring
End gap limit
0.55 mm (0.0217 in)
2nd ring
End gap limit
0.80 mm (0.0315 in)
a
b
Piston pin outside diameter
18.991–19.000 mm (0.7477–
0.7480 in)
Limit
18.971 mm (0.7469 in)
Piston pin bore inside diameter
19.004–19.015 mm (0.7482–
0.7486 in)
Limit
19.045 mm (0.7498 in)
• Piston-pin-to-piston-pin-bore clearance =
Piston pin bore diameter “b” -
Piston pin outside diameter “a”