Generac Power Systems 941-2 - Manual (Page 53)

Section 2.4
CRANKSHAFT AND CAMSHAFT
Figure 6. Bearing Bore in Crankcase Cover
COMPRESSION RELEASE MECHANISM
A mechanical compression release is provided on the
camshaft. See Figure 7. A PIN extends over the cam
lobe. This PIN pushes on the tappet, to lift the valve
and relieve compression for easier cranking. When
the engine starts, centrifugal force moves the FLY-
WEIGHT outward against SPRING force. The PIN will
then drop back and allow the engine to run at full
compression.
Measure the amount of compression release lift at the
tappet (Figure 8).
COMPRESSION RELEASE LIFT FOR GV-220 ENGINE
(MEASURED AT TAPPET)
DESIGN LIFT: 0.020-0.047 inch (0.50-1.20mm)
WEAR LIMIT: 0.016 inch (0.406mm) Minimum
Figure 7. Compression Release Mechanism on
Camshaft
Figure 8. Measuring Compression Release Lift
INSTALLING THE CRANKSHAFT
Before installing the crankshaft, lubricate all bearing
surfaces with engine oil. Use oil seal protectors, to
prevent damage to seals during installation. Install the
crankshaft as follows:
1. Lubricate all bearing surfaces with engine oil.
2. Install the valve tappets.
3. Support both ends of the crankshaft and carefully install into
the crankcase.
4. Rotate the crankshaft until the timing mark (Figure 9) is toward
the cam gear side of the crankcase.
INSTALLING THE CAMSHAFT
Apply engine oil to the camshaft main bearing and to
bearing bore in crankcase. Carefully install the
camshaft into the crankcase camshaft bore.
Hold the tappets out of the way during installation.
Align timing mark on camshaft gear with timing mark
on crankshaft gear (piston will be at top dead center).
See Figure 10.
NOTE: For Installation of the oil pump assembly,
oil pickup assembly and crankcase cover, see
Part 5 "ENGINE OIL & COOLING SYSTEM".
Page 2.3-7