Pramac GA20000, Owner'S Manual, Page: 37 / 48

Maintenance
Owner’s Manual for 50 Hz Air-Cooled Generator Sets 31
1. Perform “To turn the generator set OFF” in Gener-
ator Set Enable/Disable Procedure .
2. Remove front panel and intake side panel as
described in
Front Access Panel Removal and
Intake Side Panel Removal .
3. Turn off generator set fuel supply and disconnect
negative battery cable to avoid accidental startup.
4. Remove spark plug wires, and position wires away
from plugs.
5. Remove spark plugs using a 5/8 in socket wrench.
6. Remove four screws attaching one valve cover
using a 10 mm socket wrench. Remove and dis-
card gasket.
7. Verify piston is at top dead center (TDC) of its com-
pression stroke (both valves closed). To move pis-
ton to TDC, remove intake baffle at front of engine
to access flywheel nut. Use a 36 mm socket to
rotate flywheel nut clockwise, which will rotate
crankshaft. Watch piston through spark plug hole.
Piston will move up and down. Piston is at TDC
when it is at its highest point of travel.
8. See Figure 4-6 . Verify valve clearance between
rocker arm (A) and valve stem (B) with a feeler
gauge.
Figure 4-6. Check and Adjust Valve Clearance
9. Repeat steps 6–8 for second cylinder.
10. Install replacement valve cover gaskets.
11. Install valve covers.
NOTE: Start all four screws before tightening, or it will
not be possible to get all screws in place. Verify valve
cover gasket is in place.
12. Tighten fasteners to 6.8 Nm (60 in-lbs ) in a cross
pattern.
13. Install spark plugs and tighten to 25 Nm (18 ft-lbs).
14. Attach spark plug wires to spark plugs.
15. Connect negative battery cable and turn on gener-
ator set fuel supply.
16. Install intake side panel and front panel.
17. Perform “To turn the generator set back ON” in
Generator Set Enable/Disable Procedure .
Adjusting Valve Clearance
Proceed as follows to adjust valve clearance:
1. Perform “To turn the generator set OFF” in Gener-
ator Set Enable/Disable Procedure .
2. Remove front panel and intake side panel as
described in
Front Access Panel Removal and
Intake Side Panel Removal .
3. Turn off generator set fuel supply and disconnect
negative battery cable to avoid accidental startup.
4. Remove spark plug wires and position wires away
from plugs.
5. Remove spark plugs using a 5/8 in socket wrench.
6. Use a 10 mm socket wrench to remove four screws
attaching valve cover. Remove and discard gasket.
7. Verify piston is at TDC of its compression stroke
(both valves closed).
8. See Figure 4-6 . Loosen rocker jam nut (C) with a
13 mm wrench.
9. Turn pivot ball stud (D) using a 13 mm wrench
while inspecting clearance between rocker arm
and valve stem with feeler gauge. Adjust clearance
as per Specifications .
NOTE: Hold rocker arm jam nut in place as pivot ball
stud is turned.
10. When valve clearance is correct, hold pivot ball
stud in place with a wrench and tighten rocker arm
jam nut. Tighten jam nut to 19.68 Nm (174 in-lbs ).
11. After tightening jam nut, verify valve clearance did
not change.
12. Install new valve cover gasket.
13. Install valve cover. Tighten fasteners to 6.8 Nm (60
in-lbs ) in a cross pattern.
NOTE: Start all four screws before tightening, or it will
not be possible to get all screws in place. Verify valve
cover gasket is in place.
14. Repeat process for other cylinder if necessary.
15. Install spark plugs and tighten to 25 Nm (18 ft-lbs).
16. Attach spark plug wires to spark plugs.
17. Connect negative battery cable and turn on gener-
ator set fuel supply.
18. Install intake side panel and front panel.
19. Perform “To turn the generator set back ON” in
Generator Set Enable/Disable Procedure .
C
D
A
B
002380