TOHATSU BFT75A Service Manual page 420

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PISTON RING THICKNESS
Check the piston ring for damage (scores, scratches,
etc.).
Measure the piston ring thickness.
STANDARD:
TOP
SECOND
The oil rings are the combination rings.
Replace the side rails and the spacer as a set when
either the top or second ring needs replacement.
PISTON RING GROOVE WIDTH
Check the piston ring grooves for uneven wear,
damage or restricted oil hole.
Measure the piston ring groove width.
STANDARD:
TOP [1]
SECOND [2]
OIL [3]
PISTON RING SIDE CLEARANCE
Set the piston ring on the piston properly so it is almost
flush with the piston outer surface.
Measure the piston ring side clearance.
STANDARD:
TOP
SECOND
SERVICE LIMIT:
TOP
SECOND
If the measurement exceeds the service limit, replace
the piston ring with a new one and recheck.
If the measurement still exceeds the service limit after
replacing the piston ring, replace the piston with a new
one.
0.970 – 0.985 mm
(0.0382 – 0.0388 in)
1.175 – 1.190 mm
(0.0463 – 0.0469 in)
1.050 – 1.060 mm
(0.0413 – 0.0417 in)
1.220 – 1.230 mm
(0.0480 – 0.0484 in)
2.005 – 2.020 mm
(0.0789 – 0.0795 in)
0.065 – 0.090 mm
(0.0026 – 0.0035 in)
0.030 – 0.055 mm
(0.0012 – 0.0022 in)
0.150 mm (0.0059 in)
0.130 mm (0.0051 in)
CYLINDER BLOCK
[1]
[2]
[3]
15-19