(3)
Replacing pistons
Replace the piston with a new one if the measure
ment exceeds the service limit. Where any pistons
have to be replaced, the variance in weight among
the pistons must not exceed the limit. It is
recommended that cylinder number be stamped
on a piston selected to be used in a particular
cylinder for convenience.
When the cylinder sleeves are bored to the oversize,
pistons and piston rings of the same oversize
should be used. There are three oversizes for pistons
and piston rings, namely, +0.25 mm (0.00984 in.),
+0.50 mm (0.01969 in.) and 0.75 mm (0.0295 in.).
(4)
Piston rina pps
Check the ring gap with a thickness gauge by
placing the ring in a new cylinder sleeve, and
pushing the piston true and square in the bore.
Specifications
Item
Front of engine
t
Piston -ight
Piston weight marking
Piston ring
Gap
Checking piston ring gap
Unit: mm (in.)
Standard
Service
limit
0.30-0.50
1.5
Piston ring gap
(0.0118 -0.0197)
(0.059)
( S) Piston ring grooves
Insert the compreuion and oil rings of known
thicknesses into the grooves, and measure the
side clearance with a straightedge and thickness
gauge@.
Measuring piston ring groove
Specifications
Unit· mm (in )
Item
Standard
Repair
limit
Fit in ring
No. 1 compression
0.050 -0.085
0.20
ring
(0.00197 -0.00335 (0.0079)
grooves
No. 2 compression ring
0.025 -0.060
0.15
Oil ring
(0.00098 -0.00236) (0.0059)