SECTION 10: PISTON, RINGS AND ROD
39
a. A quick check for wear in (a) the wrist pin, (b) wrist pin
bore in piston or (c) wrist pin bore in rod is to check for
looseness or play with the piston assembled to the rod.
b. Looseness or play indicates a worn wrist pin, or a worn
wrist pin bore in the piston or rod.
NOTE: Tolerances between the wrist pin and wrist pin
bores are extremely close. Always apply engine oil to
the pin and its bores prior to installation.
4. Check wrist pin and wrist pin bores for wear.
a. Measure the outside diameter of the wrist pin.
b. Measure the inside diameter of the wrist pin bore in
piston.
c. Measure the inside diameter of the wrist pin bore in con-
necting rod.
d. Measure the wrist pin length.
5. If excessive wear is found, replace the worn part.
WRIST PIN OUTSIDE DIAMETER
GN-190, GN-191, GN-220
0.708-0.709 inch (17.989-18.000mm)
WRIST PIN LENGTH
GN-190, GN-191, GN-220
2.196-2.213 inch (55.8-56.2mm)
DIAMETER OF WRIST PIN BORE IN PISTON
GN-190, GN-191, GN-220
0.708-0.709 inch (18.000-18.011mm)
DIAMETER OF WRIST PIN BORE IN ROD
GN-190, GN-101, GN-220
0.709-0.710 inch (18.02-18.03mm)
PISTON RINGS
GENERAL:
The following general rules pertaining to piston rings must
always be complied with:
• Always replace piston rings in sets.
• Use a ring expander to remove or install piston rings, or
breakage could result. Do not spread the rings too far
apart or they might break.
• Use a ring compressor when installing the piston into the
cylinder.
• When installing NEW rings, deglaze the cylinder walls
with a commercially available deglazing tool.
DESCRIPTION:
A piston ring set consists of (a) a top compression ring, (b)
a second compression ring and (c) an oil ring assembly.
• The OIL CONTROL RING is a three-piece assembly consisting
of two oil rails and an oil spacer ring. Oil rails have a
rounded face and may be installed with either side up.
• The SECOND COMPRESSION RING has an inside chamfer.
This chamfer must face upward when installing the ring.
• The TOP COMPRESSION RING has a barrel shaped face and
can be installed with either side facing up.
Figure 10.4 — Location of Rings in Piston Grooves
RING END GAP:
Inside the cylinder, locate a point that is 2.75 inches (70mm)
down from the top of the cylinder (about halfway down). Place
ring into cylinder and use the piston to push the ring down
to the stated depth. Check ring end gap with a feeler gauge.
See Figure 10.5.
If the ring end gap is excessive, the cylinder is worn exces-
sively. See next page for ring gap tolerances.
TOP RING END GAP
GN-190, GN-191, GN-220
0.005-0.016 inch (0.15-0.40mm)
SECOND RING END GAP
GN-190, GN-191, GN-220
0.006-0.016 inch (0.15-0.40mm)
OIL RING END GAP
GN-190, GN-191, GN-220
0.015-0.055 inch (0.38-1.40mm)
NOTE: Oversize pistons and rings are not available. If
the cylinder is worn or damaged, the crankcase must
be replaced.
TOP COMPRESSION RING
EITHER SIDE UP
PISTON (CUTAWAY VIEW)
OIL CONTROL RING
EITHER SIDE UP
2ND COMPRESSION RING
CHAMFER FACING UP
Содержание GN190H
Страница 1: ......
Страница 6: ...4 DIMENSIONS AND FEATURES G E N E R A C PTO SIDE VIEW BOTTOM VIEW MOUNTING HOLES...
Страница 7: ...5 DIMENSIONS AND FEATURES FRONT VIEW...
Страница 8: ...6 DIMENSIONS AND FEATURES G E N E R A C STARTER SIDE VIEW PTO CRANKSHAFT OPTIONS VIEW...
Страница 15: ...13 NOTES...
Страница 23: ...21 NOTES...
Страница 39: ...NOTES 37...
Страница 62: ...Printed in U S A Copyright 1999 Generac Power Systems Inc...
