5.14
Section 5
Fuel System and Governor
The regulating pin contacts the tab on the cross shaft,
causing the shaft to rotate when the engine speed
changes. One end of the cross shaft protrudes through
the side of the crankcase. Through external linkage
attached to the cross shaft, the rotating action is
transmitted to the throttle lever of the carburetor.
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 are in ‘‘equilibrium’’ during operation, holding the
engine speed constant.
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. This action takes place very
rapidly, so a reduction in speed is hardly noticed. As
the speed reaches the governed setting, the governor
spring tension and the force applied by the regulating
pin will again be in equilibrium. This maintains the
engine speed at a relatively constant level.
The governor speed setting is determined by the
position of the throttle control. It can be variable or
constant, depending on the application.
Initial Adjustment
Make this initial adjustment whenever the governor
arm is loosened or removed from the cross shaft. To
ensure proper setting, make sure the throttle linkage is
connected to the governor arm and the throttle lever
on the carburetor. The carburetor and air cleaner
should be positively secured on the mounting studs,
eliminating any possible movement when adjustment
is being made. See Figure 5-18.
1. Pull the governor lever away from the
carburetor (wide open throttle).
2. Insert a nail in the cross shaft hole or grasp the
cross shaft flats with a pliers and turn the shaft
counterclockwise as far as it will go.
3. Tighten the hex nut securely.
Sensitivity Adjustment
Governor sensitivity is adjusted by repositioning the
governor spring in the holes in the governor lever. If
speed surging occurs with a change in load, the
governor is set too sensitive. If a big drop in speed
occurs when normal load is applied, the governor
should be set for greater sensitivity.
Remote Throttle and Choke Adjustment
1. Adjust the throttle lever. See this section.
2. Install remote throttle cable in hole in the throttle
lever. See Figure 5-19.
Figure 5-18. Governor Adjustment (Air Cleaner
Removed for Clarity).
Governor
Lever
Hex Nut
Cross Shaft
Figure 5-19. Remote Throttle and Choke
Adjustment.
3. Install remote choke cable in hole in the choke
lever.
4. Secure remote cables loosely with the cable
clamps.
5. Position the throttle cable so that the throttle lever
is against stop.
6. Tighten the throttle cable clamp.
7. Position the choke cable so that the carburetor
choke plate is fully closed.
8. Tighten the choke cable clamp.
9. Check carburetor idle speed. See Adjusting
Carburetor in this section.
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