Service Manual

INSPECTION AND REPAIR OF BASIC ENGINE
6-18
4.3 Measuring piston outside diameter
(1) Measure the piston outside diameter of the piston skirt
at right angles to the piston pin. If it exceeds the limit,
replace the piston with a new piston. When replacing
piston, be sure to select a piston so that the piston
weight difference in one engine is kept within the
permissible range.
(2) The piston weight is stamped on the top of piston head.
The piston weight is stamped on the top of piston head.
Measuring piston outside diameter
Piston weight stamp location
4.4 Measuring piston ring end gap
Place the piston ring in a gauge or a new sleeve to measure
the ring end gap. If the limit is exceeded, replace all the
rings as a set.
Note: Use a piston to push the piston ring squarely into the
gauge or the sleeve.
Measuring piston ring end gap
Item Nominal Standard Limit
Piston
outside
diameter
(at piston
skirt)
STD
ø 94 mm
[3.70 in.]
93.955 to 93.985 mm
[3.6990 to 3.7002 in.]
93.770 mm
[3.6917 in.]
0.25 mm
[0.0098 in.]
/OS
94.205 to 94.235 mm
[3.7089 to 3.7100 in.]
94.020 mm
[3.7016 in.]
0.50 mm
[0.0197 in.]
/OS
94.455 to 94.485 mm
[3.7187 to 3.7199 in.]
94.270 mm
[3.7114 in.]
Weight difference in one engine
5 g
[0.2 oz.] or less
-
Measuring point
Direction at right
angles to piston pin
Identification
mark
Front mark
Weight stamp
Number stamp
Item Standard Limit
Closed
gap
of ring
No. 1
compression ring
0.30 to 0.50 mm
[0.0118 to 0.0197 in.]
1.50 mm
[0.0591 in.]
No. 2
compression ring
0.50 to 0.70 mm
[0.0197 to 0.0276 in.]
Oil ring
0.30 to 0.50 mm
[0.0118 to 0.0197 in.]
End gap
Thickness gauge