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CARBURETOR ADJUSTMENTS
WARNING
If any adjustments are made to the engine
while the engine is running {e.g., carbure¬
tor), disengage ail clutches and blades.
Keep clear of all moving parts and be careful
of heated surfaces and muffler.
WARNING
To avoid injury or an accident, be sure the
brake pedal is in the locked position,
transmission is in neutral, and any equip¬
ment is disengaged before starting engine to
make carburetor adjustments.
WARNING
Carbon monoxide fumes can be fatal! Do
not make any adjustments to the carburetor
in a confined area such as a storage build¬
ing. Move the tractor outside into the air.
■^NOTE
Model 1872 tractors will be equipped with
either a fixed jet or an adjustable carburetor.
Model 2072 tractors will be equipped with
fixed jet carburetors only. The difference
between the carburetors is that the fixed jet
carburetor does not have a main fuel adjust¬
ment; therefore the fixed jet carburetor has
only two adjustment screws.
The carburetor is adjusted at the factory and under
normal operating conditions it will not require read¬
justing. However, if the engine does not operate
properly, what may appear to be a faulty carburetor
adjustment is in many cases a clogged air filter. This
possibility should be ruled out before attempting to
readjust carburetor. Refer to "MAINTENANCE" sec¬
tion in this manual.
To prevent possible damage to the carburetor nee¬
dles, be very careful closing the carburetor needles
before basic adjustments are made. Improper adjust¬
ment of the carburetor may result in engine damage.
MAIN FUEL ADJUSTMENT
(1872 Tractor with Adjustable Carburetor Only)
Preliminary setting - turn screw out 2 1/2 turns. Final
setting - start engine and raise engine speed to max¬
imum governed, no load speed. Turn screw in just
until engine speed decreases and note the position of
the screw. Now turn the screw out. The engine
speed will first increase, but then decrease as screw
is turned out. Note the position of screw when engine
spread starts to decrease. Set the screw midway
between the two points noted above.
IDLE SPEED ADJUSTMENT
(1872 and 2072 Tractors)
Run engine at maximum governed, no load speed for
a minimum of 30 seconds, then allow engine speed to
fall to idle or pul throttle into idle position. Set engine
speed to 1200 (+ or -75 RPM) by turning the idle
speed screw in or out.
IDLE FUEL ADJUSTMENT
(1872 and 2072 Tractors)
Set the idle fuel mixture by turning the idle fuel screw
out, from the closed position, 3/4 to 1-1/4 full turn.
1
Figure 23.
1872 Tractor With Adjustable
Carburetor
1
.
Main Fuel Adjustment Screw
2.
Idle Fuel Adjustment Screw
3.
Idle Speed Adjustment Screw
2
Figure
24, All 2072 Tractors and 1872 Tractors
With Fixed Jet
1.
Idle Fuel Adjustment Screw
2.
Idle Speed Adjustment Screw
18
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