Yamaha F400A 2022 - Checking the Piston Ring Side Clearance; Checking the Piston Pin Boss Inside Diameter; Checking the Piston Pin Diameter

Cylinder block
7-81
Checking the piston ring side
clearance
1. Measure:
• Piston ring side clearance
Out of specification → Check the piston
ring grooves and piston ring.
See “Checking the piston ring groove”
(7-80) and “Checking the piston ring”
(7-79).
Checking the piston pin boss inside
diameter
1. Measure:
• Piston pin boss inside diameter “a”
Out of specification → Replace.
TIP:
When measuring the piston pin boss inside di-
ameter, do not measure it at the ring groove
“b” or oil groove “c”.
Checking the piston pin diameter
1. Measure:
• Piston pin outside diameter “a”
(at measuring points “b”, “c”, and “d”, and
in directions “e” and “f”)
Below specification → Replace.
a. Top ring side clearance
b. 2nd ring side clearance
c. Oil ring side clearance
Piston ring side clearance
Top ring
Side clearance
0.03–0.08 mm (0.0014–0.0032
in)
Limit
0.130 mm (0.0051 in)
2nd ring
Side clearance
0.03–0.07 mm (0.0012–0.0028
in)
Limit
0.110 mm (0.0043 in)
Oil ring
Side clearance
0.04–0.12 mm (0.0016–0.0047
in)
a
b
c
Pin boss inside diameter
22.011–22.018 mm (0.8666–
0.8668 in)
Limit
22.038 mm (0.8676 in)
a
b
c
c
a
b
e
f
c
d