3-66 ENGINE
PISTON-TO-CYLINDER CLEARANCE
Subtract the piston diameter from the cylinder bore diameter. If
the piston-to-cylinder clearance exceeds the service limit, rebore
the cylinder and use an oversize piston or replace both the cylin-
der and the piston.
# Piston-to-cylinder clearance
Service Limit: 0.12 mm (0.0047 in)
Piston oversize: 0.5, 1.0 mm
PISTON-RING-TO-GROOVE CLEARANCE
Measure the side clearances of the 1st and 2nd piston rings us-
ing the thickness gauge. If any of the clearances exceed the limit,
replace both the piston and piston rings.
" 09900-20803: Thickness gauge
09900-20205: Micrometer (0 – 25 mm)
# Piston-ring-to-groove clearance
Service Limit: (1st) : 0.18 mm (0.007 in)
(2nd) : 0.15 mm (0.006 in)
# Piston ring groove width
Standard: (1st) : 1.01 – 1.03 mm (0.040 – 0.041 in)
(2nd) : 1.01 – 1.03 mm (0.040 – 0.041 in)
(Oil) : 2.01 – 2.03 mm (0.079 – 0.080 in)
# Piston ring thickness
Standard: (1st) : 0.975 – 0.990 mm (0.038 – 0.039 in)
(2nd) : 0.970 – 0.990 mm (0.038 – 0.039 in)
PISTON RING FREE END GAP AND PISTON RING END
GAP
Measure the piston ring free end gap using vernier calipers. Next,
fit the piston ring squarely into the cylinder and measure the pis-
ton ring end gap using the thickness gauge. If any of the mea-
surements exceed the service limit, replace the piston ring with a
new one.
" 09900-20102: Vernier calipers
# Piston ring free end gap
Service Limit: (1st) : 8.0 mm (0.31 in)
(2nd) : 9.6 mm (0.38 in)
" 09900-20803: Thickness gauge
# Piston ring end gap
Service Limit: (1st) : 0.5 mm (0.02 in)
(2nd) : 1.0 mm (0.04 in)
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