Cylinder bore:
Using a cylinder bore gauge, measure the diameter of each bore
in two directions, longitudinal and transverse, at three places,
top, middle and bottom, to obtain a total of 6 readings. On the ba-
sis of these readings taken on each bore, determine whether the
maximum difference in diameter between any two bores ex-
ceeds the limit. If the limit, stated below, is exceeded or if the
bore wall is badly scored or burned, re-bore all cylinders to the
next oversize and use oversize pistons in engine reassembly.
When replacing the pistons or installing oversize pistons, be
sure that the piston-to-cylinder clearance comes within the
stated range:
CAUTION:
If any one of the three cylinders has to be re-bored, re-
bore the three to the same next oversize. This is neces-
sary for the sake of uniformity and balance.
Piston and piston rings
Piston diameter:
Piston-to-cylinder clearance, mentioned above, is equal to the
bore diameter minus the piston diameter, which is to be mea-
sured by measuring at the level of the piston in the direction
transverse to piston pin axis, as shown in below figure. This level
from the skirt end is 30 mm (1.18 in.) high.
“a”. 30 mm (1.18 in.)
6A-26
ENGINE MECHANICAL (F8B ENGINE)
Piston oversize
0.25 mm (0.0098 in.)
Piston oversize
0.50 mm (0.0196 in.)
Wear limit on bore
0.05 mm (0.0020 in.)
Piston-to-cylinder clearance
0.045 – 0.055 mm
(0.0018 – 0.0022 in.)
Standard
68.450 – 68.475 mm
(2.6949 – 2.6959 in.)
Piston diameter
Oversize:
0.25 mm
(0.0098 in.)
68.720 – 68.740 mm
(2.7055 – 2.7063 in.)
0.50 mm
(0.0196 in.)
68.970 – 68.990 mm
(2.7154 – 2.7161 in.)
