Yamaha YZ-Serie Fahrer- Und Wartungshandbuch Seite 234

CYLINDER HEAD, CYLINDER AND PISTON
5PA40490
5PA40500
5PA40510
5PA40520
5PA40530
3. Measure:
Cylinder bore "C"
G
Use cylinder gauge 1.
Out of limit → Replace.
NOTE:
Measure the cylinder bore "C" in parallel (A, B,
C) to and at right angles to the crankshaft (a, b).
Then, find the average of the measurements.
Cylinder 47.500 ~ 47.514 mm
bore "C" (1.8701 ~ 1.8706 in)
Taper "T"
C = Maximum Aa ~ Cb
T = (Maximum Aa, or Ab) –
(Maximum Ba, or Bb)
Piston
1. Eliminate:
Carbon deposits
G
From the piston crown a and ring groove
b.
2. Inspect:
Piston wall
G
Score marks → Replace.
3. Measure:
Piston skirt diameter
G
Use micrometer 1.
Measure the specific distance a from the
bottom edge.
Out of specification → Replace.
Piston dia.:
47.457 ~ 47.472 mm
(1.8684 ~ 1.8690 in)
Distance a:
20 mm (0.79 in)
Piston pin and small end bearing
1. Inspect:
Piston pin
G
Small end bearing
G
Signs of heat discoloration → Replace.
4 - 19
ENG
Standard Wear limit
47.6 mm
(1.8740 in)
0.05 mm
–
(0.0020 in)