Checking The Piston Rings - Yamaha EH63 Service Manual

PISTONS, CAMSHAFT, CRANKCASE, AND CRANKSHAFT
4.
Check:
• Check that the piston pin enters smoothly into the
piston pin hole.
TIP
If the piston pin fits too tight into the piston, check the pis-
ton pin hole. If there is any protrusion, use a knife or
scraper to gently remove it so that piston pin can be
pushed in smoothly with your fingers.

CHECKING THE PISTON RINGS

The following procedure applies to all of the piston rings.
1.
Measure:
• Piston ring side clearance
Out of specification  Replace the piston and pis-
ton rings as a set.
TIP
Before measuring the piston ring side clearance, eliminate
any carbon deposits from the piston ring grooves and pis-
ton rings.
Piston ring
Top ring
Side clearance:
Limit:
2nd ring
Side clearance:
Limit:
2.
Install:
• Piston ring
a
(into the cylinder)
TIP
Use the piston crown to level the piston ring near bottom of
cylinder "a", where cylinder wear is lowest.
b
b. Upper part of cylinder
3.
Measure:
• Piston ring end gap
Out of specification  Replace the piston rings as a
set.
3-57
0.05–0.09 mm (0.0019–0.0035 in)
0.14 mm (0.0055 in)
0.03–0.07 mm (0.0012–0.0028 in)
0.13 mm (0.0051 in)
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