Checking The Piston Rings - Yamaha TMAX 2020 Service Manual

a
G089001
a. 8.0 mm (0.31 in) from the bottom edge of
the piston
Piston
Diameter
69.975–69.990 mm
(2.7549–2.7555 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 -
Piston skirt diameter
Piston-to-cylinder clearance
0.010–0.035 mm (0.0004–0.0014
in)
f. If out of specification, replace the cylinder,
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.
b
CYLINDER AND PISTONS
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)
G089002
2. Install:
• Piston ring
(into the cylinder)
TIP
Use the piston crown to level the piston ring near
the bottom of the cylinder where the cylinder
wear is lowest.
3. Measure:
• Piston ring end gap
Out of specification  Replace the piston ring
set.
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 ring
Top ring
End gap limit
0.50 mm (0.0197 in)
2nd ring
End gap limit
0.85 mm (0.0335 in)
5-32