Honda G100K2 Applications Manual page 21

POWER OUTPUT
GOVERNOR SYSTEM
The governor system automatically maintains a constant engine speed regardless of changes in engine loading.
Three types of governor systems are commonly used: centrifugal, air-vane or electric governor.
Honda general purpose engines use a centrifugal governor system.
At a certain engine speed setting (by the control lever) there is a balance between the governor spring force and
the centrifugal force of the governor weights exerted on the governor arm.
When engine speed increases due to reduced loading, the governor weight is moved by centrifugal force towards
the outer end of the radius.
This in turn closes the throttle valve via the link rod and engine speed is reduced.
When engine speed decreases, the action of the governor is opposite to the above and engine rpm is increased.
The two sequences occur repeatedly to maintain constant speed regardless of changes in engine loading.
COEFFICIENT OF GOVERNOR FLUCTUATION
This chart shows engine speed changes when the load
(rated load) is suddenly removed during operation.
The following 3 items are to be considered when checking
governor function.
a. Momentary value = Momentary max. speed – Speed with rated load x 100 %
b. Set value = Speed with no load –Speed with rated load x 100 %
c. Setting time = t (sec)
A good governor characteristic will show small values for a, b and
c. An engine equipped with such a governor will show little change
in rpm and will return immediately to the set value when a change
in load occurs.
Governor
arm shaft
Governor slider
Governor weight
CLOSE
Throttle valve
Speed with rated load
Speed with rated load
Pinch bolt nut
Governor spring
Governor rod
Throttle lever
LOW
HIGH
NOTE
Arrows indicate direction when engine speed increases
Rpm
Momentary
value
Rated
load
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Governor arm
No load
Set value
Setting time
Time