Inspection Of Piston Ring Side Clearance; Inspection Of Piston Rings - TOHATSU MFS 60A Service Manual

30) Inspection of Piston Ring Side Clearance

1. Measure piston side clearance. Replace piston and piston
rings as a set if the clearance is over specified value.
Piston Side Clearance :
Top Ring a : 0.04 to 0.08 mm (0.0016 to 0.0031 in)
Second Ring b : 0.01 to 0.05 mm (0.0004 to 0.0020 in)
Oil Ring c : 0.03 to 0.13 mm (0.0012 to 0.0051 in)
Functional Limit :
Top Ring a : 0.10 mm (0.0039 in)
Second Ring b : 0.07 mm (0.0028 in)
Oil Ring c : 0.15 mm (0.0059 in)

31) Inspection of Piston Rings

Push piston ring 1 into ring gauge 70.000 mm (2.75591
1
in) parallel to top edge. Measure at the top or bottom of
cylinder bore with no wear.
2. When ring gauge is not available, use piston crown to push
piston ring 1 into to cylinder.
Measure piston ring closed gap a. Replace if the gap is over
3.
specified value.
Piston Ring Closed Gap a :
Top Ring : 0.20 to 0.35 mm (0.0079 to 0.0138 in)
Second Ring : 0.35 to 0.50 mm (0.0138 to 0.0197 in)
Oil Ring : 0.20 to 0.70 mm (0.0079 to 0.0276 in)
Functional Limit :
Top Ring : 0.55 mm (0.0217 in)
Second Ring : 0.70 mm (0.0276 in)
Oil Ring : 1.00 mm (0.0394 in)
Replace oil ring when top ring or second ring is
replaced.
4st 60 2019
1
a
a
b
c
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