5-40 ENGINE TOP END
If a new piston is used, use new piston ring.
Apply molybdenum disulfide oil solution to the oil ring ex-
pander, and install the oil ring expander [A] in the bottom
piston ring groove so the ends [B] not butt together.
Apply molybdenum disulfide oil solution to the oil ring steel
rails, and install the oil ring steel rails, one above the ex-
pander and one below it.
Spread the rail with your thumbs, but only enough to fit
the rail over the piston.
Release the rail into the bottom piston ring groove.
The oil ring rails have no "top" or "bottom."
Apply molybdenum disulfide oil solution to the piston
Do not mix up the top and second ring.
Install the top ring [A] so that the "1T" mark [B] faces up.
Install the second ring [C] so that the "2T" mark [D] faces
Install the piston with its dent mark facing forward.
Apply molybdenum disulfide oil solution to the piston pins
and piston journals.
Fit a new piston pin snap ring into the side of the piston
so that the ring opening [A] does not coincide with the slit
[B] of the piston pin hole.
When installing the piston pin snap ring, compress it only
enough to install it and no more.
Do not reuse snap rings, as removal weakens and
deforms them. They could fall out and score the
Install the cylinder (see Cylinder Installation).
Cylinder Wear Inspection
Since there is a difference in cylinder wear in different di-
rections, take a side-to-side and a front-to-back measure-
ment at each of the two locations (total of four measure-
ments) as shown.
If any of the cylinder inside diameter measurements ex-
ceeds the service limit, replace the cylinder.
10 mm (0.39 in.) [A]
60 mm (2.36 in.) [B]
Cylinder Inside Diameter
76.994 ∼ 77.006 mm (3.0313 ∼ 3.0317 in.)
Service Limit: 77.09 mm (3.035 in.)