Generac Power Systems 941-2 - Manual (Page 49)

Section 2.3
PISTON, RINGS, CONNECTING ROD
Figure 7. Ring Locations in Piston Grooves
CHECKING PISTON RING END GAP:
To check piston rings end gap, proceed as follows
(see Figure 8):
1. Locate a point inside the cylinder that is 2.75 inches (70mm)
down from top of cylinder. This is approximately half-way
down.
2. Place the ring into the cylinder. Use the piston to push the ring
squarely into the cylinder to the proper depth.
3. Use a feeler gauge to measure the ring end gap. If end gap is
excessive, rebore the cylinder to take oversize parts.
TOP RING END GAP (GV-220)
DESIGN GAP: 0.005-0.016 inch (0.15-0.40mm)
WEAR LIMIT: 0.024 inch (0.60mm) Maximum
SECOND RING END GAP (GV-220)
DESIGN GAP: 0.006-0.016 inch (0.15-0.40mm)
WEAR LIMIT: 0.024 inch (0.60mm) Maximum
OIL RING END GAP (GV-220)
DESIGN GAP: 0.015-0.055 inch (0.38-1.40mm)
WEAR LIMIT: 0.062 inch (1.60mm) Maximum
Figure 8. Ring End Gap
CONNECTING ROD
The connecting rod is manufactured of die cast alu-
minum. Alignment marks are provided on the rod and
on the connecting rod cap. Be sure to align these
marks when assembling the rod to the crankshaft.
Connecting rod bolts are of the "washerless" type.
The connecting rod and the connecting rod cap are a
matched set and must be replaced as a matched set.
Figure 9. Connecting Rod
ASSEMBLY AND INSTALLATION
ASSEMBLY:
Use a ring expander when installing rings into the pis-
ton ring grooves. Install the OIL RING ASSEMBLY
first. Then, install the second compression ring with
its Inside chamfer facing up. Finally, install the top
compression ring.
When assembling the piston, connecting rod and
wrist pin, the assembly marks on the piston must be
toward the flywheel side of the engine.
Coat the wrist pin, wrist pin bore in piston, and wrist
pin bore in the rod with engine oil. Install one snap
ring into the piston's wrist pin bore. Then, assemble
the piston to the rod. Slide the wrist pin through one
piston bore, through the rod bore, and through the
second piston bore until it contacts the snap ring.
Then, install the second snap ring into the piston
bore.
INSTALLATION:
Coat the cylinder walls with engine oil, as well as the
crank throw, connecting rod bearing and connecting
rod cap bearing. Then, install the rod and piston
assembly as follows:
1. Use a ring compressor to compress the rings into the piston
ring grooves. MAKE SURE ALL RINGS ARE FULLY COM-
PRESSED INTO THEIR GROOVES.
2. Guide the connecting rod into the cylinder, with assembly mark
on piston toward the flywheel side of engine.
3. When the ring compressor contacts top of cylinder, use a wood
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