Checking The Piston Rings - Yamaha MBK X-MAX 300 2017 Service Manual

b
b. 8.0 mm (0.31 in) from the bottom edge of the
piston
Piston
Diameter
69.962–69.985 mm (2.7544–
2.7553 in)
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.
Piston-to-cylinder clearance =
Cylinder bore "C" -
Piston skirt diameter "D"
Piston-to-cylinder clearance
0.031–0.047 mm (0.0012–0.0019
in)
f. If out of specification, replace the cylinder,
and replace the piston and piston rings as
a set.
EAS30292

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.
a
CYLINDER AND PISTON
Piston ring
Top ring
Ring side clearance
0.030–0.065 mm (0.0012–
0.0026 in)
Side clearance limit
0.115 mm (0.0045 in)
2nd ring
Ring side clearance
0.020–0.055 mm (0.0008–
0.0022 in)
Side clearance limit
0.115 mm (0.0045 in)
2. Install:
• Piston ring
(into the cylinder)
TIP
Use the piston crown to level the position ring
near the bottom of the cylinder "a" where the cyl-
inder wear is lowest.
b. Top of cylinder
3. Measure:
• Piston ring end gap
Out of specification → Replace the piston
ring.
TIP
The oil ring expander spacer end gap cannot be
measured. If the oil ring rail gap is excessive, re-
place all three piston rings.
5-34
a
b