Cylinder Block Check; Piston Check; Piston Clearance Check; Piston Ring Check - Yamaha Waverunner VXS VX1800 Service Manual

Cylinder block check

1. Measure the cylinder bore (D1–D6) at
measuring points "a", "b", and "c", and in
direction "d" (D1, D3, D5), which is parallel
to the crankshaft, and direction "e" (D2,
D4, D6), which is at a right angle to the
crankshaft. Replace the crankcase if out of
specification.
a
D
b
2
c
D
4
D
6
a. 20 mm (0.79 in)
b. 50 mm (1.97 in)
c. 80 mm (3.15 in)
Bore size
86.000–86.015 mm (3.3858–3.3864 in)
Limit
86.100 mm (3.3898 in)

Piston check

1. Measure the piston diameter "a" at the
specified measuring point "b".
a
b
Diameter
85.915–85.930 mm (3.3825–3.3831 in)
Measuring point
9.5 mm (0.37 in)
2. Measure the piston pin boss bore diameter
"a". Replace if out of specification.
D
1
d
D
e
3
D
5
Crankcase, connecting rod, and piston
TIP:
When measuring the piston pin boss inside di-
ameter "a", do not measure it at the oil grooves
"b" or piston pin slot "c".
c
b
Pin boss bore diameter
22.004–22.015 mm (0.8663–0.8667 in)
Limit
22.045 mm (0.8679 in)

Piston clearance check

1. Measure the piston diameter. See "Piston
check" (5-76).
2. Measure the cylinder bore. See "Cylinder
block check" (5-76).
3. Calculate the piston clearance. Replace
the piston or crankcase if out of specifica-
tion.
Piston clearance = maximum cylinder bore
- piston outside diameter
Piston clearance
0.080–0.090 mm (0.0032–0.0035 in)
Limit
0.200 mm (0.0079 in)

Piston ring check

1. Measure piston ring dimensions B and T.
Replace the piston rings as a set if out of
specification.
5-76
a
b