Yamaha XSR900 2022, Service Manual

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5-72
CONNECTING RODS AND PISTONS
b. If out of specification, replace the cylinder,
and replace the piston and piston rings as a
set.
c. Measure piston skirt diameter “b” with the
micrometer.
d. If out of specification, replace the piston and
piston rings as a set.
e. Calculate the piston-to-cylinder clearance
with the following formula.
f. If out of specification, replace the cylinder,
and replace the piston and piston rings as a
set.
EAS30748
CHECKING THE PISTON RINGS
1. Measure:
• Piston ring side clearance
Out of specification
→
Replace the piston
and piston rings as a set.
TIP
Before measuring the piston ring side clearance,
eliminate any carbon deposits from the piston
ring grooves and piston rings.
2. Install:
• Piston ring
(into the cylinder)
TIP
Use the piston crown to level the piston ring near
bottom of cylinder, where cylinder wear is low-
est.
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.
Piston
Diameter
77.975–77.990 mm ( 3 .0699–
3 .0705 in)
a. 9.0 mm (0.35 in) from the bottom edge of the
piston
Piston-to-cylinder clearance = Cylinder bore
“C” - Piston skirt diameter “b”
Piston-to-cylinder clearance
0.010–0.0 3 5 mm (0.0004–0.0014
in)
a
b
G089001
Top ring
Side clearance limit
0.115 mm (0.0045 in)
2nd ring
Side clearance limit
0.115 mm (0.0045 in)
Top ring
End gap limit
0.50 mm (0.0197 in)
2nd ring
End gap limit
1.15 mm (0.045 3 in)
a. Bottom of cylinder
b. Upper of cylinder
G089002
a
b
G089003