Specifications

83
Use a ring expander to remove and replace the rings. Do
not spread the rings too wide or breakage will result.
If the top compression ring has an inside chamfer, this
chamfer must face UP. The second compression ring will
have either an inside chamfer or an outside notch. The
rule to follow is an inside chamfer always faces up. An
outside notch (diag. 31) will face down or towards the skirt
of the piston.
The oil control ring can be installed with either side up. The
expander (if equipped) end gap and the ring end gap should
be staggered.
Emission Rings
Used on TVS, LEV, H35, VLV, HM80 and TVXL195
engines that comply with emission standards. These rings
have a narrower width and a different profile (barrel faced).
Barrel faced rings may be installed in either direction. The
underside of the oil control ring utilizes a coil type expander.
These rings conform better to the cylinder allowing for better
oil control by wiping the cylinder wall cleaner. The coiled
expander ring helps create a more uniform load on the
cylinder wall which gives a more consistent distribution of
oil. NOTE: The use of these rings on a standard non-
emission piston will cause ring breakage due to its wider
ring grooves.
Connecting Rods
Some engine models have offset piston pins (not
centered) to centralize the combustion force on the piston.
Engine models LAV50, HM70, HM80, HHM80, HM100,
TVM170,195, 220, have offset pistons. When installing
the connecting rod to the piston it is imperative that the
rod be installed correctly. The piston used on these models
will have either an arrow stamped above the piston pin
hole, a number cast on the inside of the piston skirt or
an arrow stamped on the top of the piston (diag. 32 &
33). All other engine models use a centered piston pin. If
the piston does not have an arrow or number cast inside,
the piston can be installed in either direction on the
connecting rod. On all engine models, the match marks
on the connecting rod must align and face out when
installing the assembly in the engine (diag. 34 & 35).
The arrow on the top of the piston must point toward the
valves when installing it in the cylinder (diag. 33). The inside
casting number (if present) must face toward the long side
of the connecting rod. If there is an arrow on the side of
the piston, the arrow must point toward the short side of
the connecting rod. (diag. 32).
On horizontal shaft engines, oil dippers are attached to
the bottom connecting rod bolt. Some engines have the
oil dipper cast in the rod cap. Consult the specification
chart for the proper rod bolt torque when installing the
cap. The rod bolts should be torqued in 50 inch pound
(5.5 Nm) increments until the specified torque is achieved.
30
2ND COMPRESSION RING
1ST COMPRESSION RING
3RD OIL
CONTROL RING
31
EMISSION RINGS
3RD OIL
CONTROL RING
1ST COMPRESSION RING
2ND COMPRESSION RING
ARROW POINTS
TOWARD THE
VALVES
33
TVM220 PISTON AND ROD
WRIST PIN
MATCH MARKS
VM70, VM100, HM70-100, V80, H80, HHM80, AND TVM SERIES
PISTON AND CONNECTING ROD ASSEMBLIES
LONG SIDE OF ROD
CASTING NUMBER
ARROW
DIRECTION
SHORT SIDE OF ROD
32
3534
MATCH MARKS
MATCH
MARKS
CHAMFER