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SECTION 6A
FUEL SYSTEMS AND GOVERNORS
9. Install the idie speed adjusting screw and spring.
install the idle fuel and main fuel adjusting
needles and springs. Tum the adjusting needles
clockwise until they bottom lightly.
NOTE:
The ends of adjusting needles are tapered
to critical dimensions.
Damage to
needles and seats will result if needles
are forced.
10. Reinstall the carburetor to the engine using a new
gasket.
11. Adjust the carburetor as outlined under the
"Adjustment" portion of this section.
GOVERNOR
Magnum engines are equipped with a centrifugal fly-
weight mechanical govemor. It is designed to hold
the engine speed constant under changing load con-
ditions. The governor gear/flyweight mechanism is
mounted within the crankcase and is driven off the
gear on the camshaft. Refer to Figure 6A-16.
Cross
Governor
Shaft
Spring
Governor Gear
Assembly
Regulating
Pin
Поетот
Carburetor
пабе
Throttle Lever
Figure 6A-16.
Centrifugal Flywelght Mechanical
Governor.
*NOTE: Earlier models only - later use bracket as
shown in Figure 6A-19.
Operation
Centrifugal force acting on the rotating govemor gear
assembly causes the flyweights to move outward as
speed increases and inward as speed decreases. As
the flyweights move outward they force the regulating
pin of the assembly to move outward. The regulating
pin contacts the tab on the cross shaft, causing the
shaft to rotate with changing speed.
One end of the
cross shaft protrudes through the top of the crank-
case. Through extemal linkage attached to the cross
shaft, the rotating action is transmitted to the throttle
plate of carburetor.
When the engine is at rest and the throttle is in the
"fast" position, the tension of the governor spring
holds the throttle valve open. When the engine Is op-
erating (governor gear assembly is rotating), the force
applied by the regulating pin against the cross shaft
tends to close the throttle valve. The governor spring
tension and the force applied by the regulating pin are
in "equilibrium" during operation, holding the engine
speed constant.
Wnen a load is applied and the engine speed (and
governor speed) decreases, the governor spring ten-
sion moves the govemor arm to open the throtlle plate
wider. This admits more fuel and restores engine
speed. (This action takes place very rapidly, so a re-
duction in speed is hardly noticed.) As the speed
reaches the govemed setting, the governor spring ten-
sion and the force applied by the regulating pin will
again be in equilibrium. This maintains engine speed
&t a relatively constant level.
Govemed speed may be at a fixed point as on con-
stant speed applications, or variable as determined by
a throttle control lever.
Adjustment
A
WARNING:
Overspeed Is Hazardous!
The maximum allowable speed for these engines is
3600 RPM, no load.
Never tamper with the governor
settings to increase the maximum speed.
Severe
personal injury and damage to the engine or equip-
ment can result if operated at speeds above
maximum.
6A.12
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