Yamaha MX775 - Page 88

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ENGINE
PISTONS, CAMSHAFT, CRANKCASE, AND CRANKSHAFT
TIP
Measure cylinder bore “C” by taking side-to-side and front-
to-back measurements of the cylinder.
b. If out of specification, replace the crankcase
assembly, and replace the piston and piston rings
as a set.
c. Measure piston skirt diameter “P” with the microm-
eter.
a = 6.0 mm (0.2362 in) from the piston bottom edge
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.
f. If out of specification, replace the crankcase
assembly, and replace the piston and piston rings
as a set.
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Bore:
80.000–80.020 mm (3.1496–3.1504 in)
Warpage limit:
80.025 mm (3.1506 in)
“C” = maximum of D
1
, D
2
, D
3
, D
4
, D
5
, D
6
P
a
Piston diameter:
79.959–79.980 mm (3.1480–3.1488 in)
Limit:
79.900 mm (3.1457 in)
Piston-to-cylinder clearance = Cylinder bore “C” – Piston skirt
diameter “P”
Piston-to-cylinder clearance:
0.033–0.047 mm (0.0013–0.0019 in)
Limit:
0.15 mm (0.0059 in)