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78/83/90 Series Horizontal Shaft Engines
58
Governor
The engine speed is controlled by a balance between
the force applied by a spring (pulling the throttle open) and
a flyweight mechanism within the engine applying force to
the governor arm (pushing the throttle closed).
See Figure 4.41.
NOTE: While the mechanism is simple and robust,
it is important to pay attention when working
on parts near the governor. Binding caused
by interference with mis-routed lines or
cables may make the governor unrespon
-
sive.
NOTE: When a governed engine “hunts”, it is gen-
erally an indication of a lean fuel/air mixture,
rather than a problem with the governor.
Governor arm
To remove the governor arm from the governor shaft:
1. Remove the fuel tank by following the steps
described in the Fuel Tank section of this chapter.
NOTE: Mark or note which holes the spring and
linkage was in to ensure they go back in the same
holes.
2. Unhook the governor spring.
3. Loosen the nut and clamp bolt. See Figure 4.42.
4. Carefully spread open the seam on the arm.
5. Carefully slide the Governor arm off of the governor
shaft.
6. Unhook the governor linage and throttle return
spring.
To install the governor arm:
1. Rotate the governor shaft clockwise until it stops.
2. Slide the arm onto the shaft. The flat on the top of the shaft should be roughly parallel to the arm.
See Figure 4.42.
NOTE: There is a hairpin clip that keeps the governor shaft from sliding into the engine. It may be necessary to
hold the shaft while sliding the arm on to prevent the hairpin clip from “popping off” and allowing the governor
shaft to fall into the engine.
3. Tighten the nut on the clamp bolt to secure the arm.
4. Attach the governor linkage and spring.
5. Adjust the governor to maintain top no-load speed as described in a previous section of this chapter.
Figure 4.41
Spring tension
Governor action
Figure 4.42
Loosen nut
Spread here
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