Yanmar 1GM User Manual page 121

MULTICYLINDER ENGINES
Bore gauge
Cylinder
block
8uface
o
115
2. Measure the cylinder bore diameter at several points
with a bore gauge (Figure 32, typical). Figure 33 shows
the points of normal cylinder wear. If dimension A ex-
ceeds dimension B by more than 0.02 rom (0.0008 in.),
rebore the cylinder and install a new piston/ring assembly.
3. If the cylinder bore is damaged or excessively worn,
rebore the cylinder bore and install a new piston. If the
piston is worn, but the cylinder bore is good, install a new
piston.
@
P"
41n.
1
"""-A--44
B
NOTE
Obtain the new piston and have it available
so the machine shop can bore the cylinder to
the correct oversize dimension.
Piston Ring FitlInstaUation
1. Check the ring gap of each piston ring. To do this, posi-
tion the ring at the bottom of the ring travel area and
square it by tapping gently with an inverted piston. See
Figure 34.
NOTE
If
the cylinder has not been rebored, check
the gap at the bottom of the ring travel,
where the cylinder is least worn.
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