30/ENGINE - WORK ON INDIVIDUAL PARTS
113
18.12
Checking/measuring the cylinder
300102-10
–
Check the O-ring of the chain adjuster for damage and wear.
» If there is damage or wear:
–
Replace the O-ring.
–
Check the cylinder bearing surface for damage.
» If the cylinder bearing surface is damaged:
–
Change the cylinder and piston.
–
Measure the cylinder diameter at several places in the
and
axes using a
micrometer to check for oval wear.
–
To determine the size, measure the cylinder at a distance
from the top edge of
the cylinder.
Guideline
Distance
55 mm (2.17 in)
Cylinder - bore diameter
Size I
102.000… 102.012 mm (4.01574…
4.01621 in)
Size II
102.013… 102.025 mm (4.01625…
4.01672 in)
300103-10
–
The cylinder size
is marked on the side of the cylinder.
400376-10
–
Check the sealing area of the cylinder head for distortion using a straight edge and
the special tool.
Feeler gauge (59029041100) (
Cylinder/cylinder head - sealing area
distortion
≤
0.10 mm (
≤
0.0039 in)
» If the measured value does not equal the specified value:
–
Change the cylinder.
18.13
Checking/measuring the piston
0
0
A
A
0
0
A
A
0
0
A
A
400484-10
–
Use the special tool to measure clearance
of the piston rings in the piston ring
groove.
Guideline
Piston ring - groove clearance
≤
0.08 mm (
≤
0.0031 in)
Feeler gauge (59029041100) (
» If clearance
is larger than the specified value:
–
Change the piston and piston rings.
–
Check/measure the cylinder. (
300099-10
–
Check the piston bearing surface for damage.
» If the piston bearing surface is damaged:
–
Change the piston and, if necessary, the cylinder.
–
Check that the piston rings can move easily in the piston ring grooves.
» If the piston ring is stiff:
Summary of Contents for 690 SMC 2008
Page 1: ...REPAIR MANUAL 2008 690 SMC EU 690 SMC AUS UK 690 SMC USA Article no 3206042en...
Page 2: ......
Page 185: ...183...
