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Piston clearance
Measure cylinder bore diameter and piston diameter to
find their difference which is piston clearance. Piston
clearance should be within spec ification as follows. If it is
out of specification, rebore cylinder and use oversize
piston.
NOTE
Cylinder bore diameters used here are
measured in thrust direction at two positions.
Piston clearance
Standard (used piston): 0.032 – 0.061 mm (0.0013 –
0.0024 in.)
Standard (new piston with coating): 0.010 – 0.051
mm (0.0004 – 0.0020 in.)
Limit: 0.161 mm (0.0063 in.)
Ring groove clearance
Before checking, piston grooves must be clean, dry and
free of carbon deposits.
Fit new piston ring (1) into piston groove, and measure
clearance between ring and ring land by using thickness
gauge (2). If clearance is ou t of specification, replace
piston.
Ring groove clearance
Piston Ring
Piston ring end gap
To measure end gap, insert piston ring (2) into cylinder
bore and then measure the gap by using thickness
gauge (1).
If measured gap exceeds limit, replace ring.
NOTE
Decarbonize and clean top of cylinder bore
before inserting piston ring.
Ring groove clearance
“a”: 7.0 mm (0.28 in.)
Standard Limit
Top ring 0.04 – 0.08 mm
(0.0016 – 0.0031 in.) 0.12 mm (0.0047 in.)
2nd ring 0.03 – 0.07 mm
(0.0012 – 0.0027 in.) 0.10 mm (0.0394 in.)
Oil ring 0.04 – 0.12 mm
(0.0016 – 0.0047 in.) —
I4RS0A140022-01
Item Standard
Limit
To p r i n g 0.20 – 0.33 mm
(0.0079 – 0.0129 in.) 0.7 mm (0.0276 in.)
2nd ring 0.43 – 0.56 mm
(0.0170 – 0.0220 in.) 1.0 mm (0.0394 in.)
Oil ring 0.10 – 0.40 mm
(0.0040 – 0.0157 in.) 0.7 mm (0.0276 in.)
“a”: 120 mm (4.72 in.)
I2RH01140159-01
I2RH01140161-01
