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Understanding and Adjusting Your Governor
Generally Governors should never need to be adjusted, unless the governor arm
has been removed or
tampered with. In the event that they do need adjusted, here is how to do
it.
One of the most important parts of your engine is the engine governor. An
improperly adjusted governor can shorten your engine's life. If
engine speed is not controlled, the engine will destroy itself. Never
run an engine over speed, especially without a load attached to it. Even
for a short period of time it can cause catastrophic failures, like blowing the magneto magnet into 100's of little pieces.
Over speeding is something that needs to be taken
care of immediately, because it can be a real hazard with metal
coming loose at high speed. This page will explain how
to adjust the mechanical governor on Briggs and Stratton and Tecumseh Engines.
First, let's understand a little more about governors and why they may
not be working right: Most complaints about governors fall into two categories:
- Engine runs too fast or too slow.
- Engine surges or hunts.
You should do an
inspection of the governor linkage and spring before trying to solve
either of these problems. Make sure everything
is operating freely and the spring is not damaged or stretched.
Also, check the governor static adjustment to see that all free play
has been removed between the spindle and carburetor. The best way to
do this is to move the throttle from idle to full open and note the
way the governor shaft moves. If it goes clockwise, then loosen the
clamp screw and with the throttle wide open turn the shaft all the
way clockwise and re-tighten the nut. Make sure the throttle moves
from idle to full open freely after making the adjustment. Refer to the
engine repair manual for exact adjustment procedures.
After you have made the above check, restart the engine and see if the
governor now operates correctly. With the engine at idle, move the
governor lever with your finger to open the throttle and it should
push the arm back toward idle if working properly. One way to do
this test is with the governor spring removed. If it still over
speeds or has no push toward idle, you probably will need to have
the internal parts checked inside the motor or recheck the static
adjustment. See your local repair
shop for this!
The other problem that often occurs is governor hunting or
surging up and down. Most of the time this is not the problem of the
governor, but a partially plugged carburetor, usually a plugged
idle circuit or worn linkage. If you can rule out these causes and
have checked the adjustments I talked about above, then you may have
a governor that is set too sensitive. In other words it reacts too
quickly and over compensates for the speed. Many governor arms have
several holes in the arm to change sensitivity. By moving the
governor spring to a hole further away from the governor shaft you
will make it less sensitive. Before playing with this, check the
repair manual for the engine you have and see if it has a way of
adjusting sensitivity. Sometimes you may have to change governor
springs, etc.
Many of the smaller lawnmowers used
what is called an "air vane governor". This type of system uses the
air flowing through the engine to operate a vane back and forth
against a spring, just like the mechanical governor does. The big
problem with air vane governors is debris sometimes collects in the system blocking air flow. When this
happens the engine will over speed. So, with an air vane system it is
very important to keep the cooling fins clean so the proper amount
of air can move through the engine. The governor spring is precisely
calibrated for an engine that has full air flow going through
it. If the air flow is blocked it can over speed the engine.
Tecumseh Engines: First The governor shaft should always be turned in the same direction
the governor arm turns to open the throttle wide open. For example, on Tecumseh
TVS, LEV, TVM, TVXL and other similar engines, the governor arm rocks in the
counter clockwise direction to close the throttle to idle. To adjust the
governor, you would loosen the screw on the bottom of the governor arm and push
the governor arm so the throttle is wide open. Then you would turn the bottom
"clip" (which is connected to the governor shaft) counter clockwise. This will
set the governor shaft on top of the governor spool. Tighten the screw and
you're done.
Briggs Engines: To adjust the governor on a Briggs and Stratton
horizontal shaft engine, you would loosen the nut on the governor arm
and push the governor arm down, clockwise. Then you would turn the
governor shaft clockwise also and tighten the nut
  
  
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