5.11
Section 5
Fuel System and Governor
5
Reassembly Procedure
Reassemble the carburetor using the following steps.
See Figure 5-6.
1. Assemble fuel inlet needle to the float tab. Install
the float, float shaft and inlet needle to the
carburetor upper body. Tighten the screw. Check
float height using the procedure found previously
in the "Adjustments" subsection.
2. Install the slow jet so the stepped end will be
toward the bottom of the carburetor. Make sure jet
is fully seated.
3. Install the low idle adjusting needle and spring.
4. Assemble the carburetor upper body and
carburetor lower body using the four screws.
Torque screws to 1.7 N·m (15 in. lb.).
5. Install the carburetor on the engine following the
procedures in Section 11 - "Reassembly".
Governor
General
The engine is equipped with a centrifugal flyweight
mechanical governor. It is designed to hold the engine
speed constant under changing load conditions. The
governor gear/flyweight mechanism is mounted inside
the closure plate and is driven off the gear on the
camshaft. The governor works as follow:
•
Centrifugal force acting on the rotating governor
gear assembly causes the flyweights to move
outward as speed increases. Governor spring
tension moves them inward as speed decreases.
Figure 5-7. Governor Linkage.
•
As the flyweights move outward, they cause the
regulating pin to move outward.
•
The regulating pin contacts the tab on the cross
shaft causing the shaft to rotate.
•
One end of the cross shaft protrudes through the
crankcase. The rotating action of the cross shaft
is transmitted to the throttle lever of the carburetor
through the external linkage. See Figure 5-7.
•
When the engine is at rest, and the throttle is in
the “fast” position, the tension of the governor
spring holds the throttle plate open. When the
engine is operating, the governor gear assembly
is rotating. The force applied by the regulating pin,
against the cross shaft, tends to close the throttle
plate. The governor spring tension and the force
applied by the regulating pin balance each other
during operation, to maintain engine speed.
•
When load is applied and the engine speed and
governor gear speed decreases, the governor
spring tension moves the governor arm to open
the throttle plate wider. This allows more fuel into
the engine, increasing engine speed. As speed
reaches the governed setting, the governor spring
tension and the force applied by the regulating pin
will again offset each other to hold a steady
engine speed.
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