CARBURETOR ADJUSTMENTS
WARNING
When making adjustments to the carburetor while the engine is running, disengage the PTO clutch and engage the brake pedal lock. Keep clear of all moving parts and be careful of all hot surfaces.
WARNING
Carbon monoxide fumes can be fatal! Do not make any adjustments to the carburetor in a confined area such as a storage building. Move the tractor outside into the air.
The carburetor is adjusted at the factory and under normal operating conditions it will not require readjusting. The high idle is set at the factory and cannot be adjusted. If the engine does not operate properly and the problem appears to be fuel system related, check the following areas before adjusting the carburetor: Refer to MAINTENANCE section.
•Check for fuel in fuel tank
•Check fuel cap vent for blockage
•Check fuel line for pinched or obstructed areas
•Check for fuel filter blockage
•Check for a clogged air filter
If, however, the engine is
The air filter element and element cover must be assembled to the carburetor when running the engine.
Adjust the carburetor idle fuel mixture in the order stated as follows (Refer to Figure 17):
NOTE
Carburetor adjustments should be made only after the engine has warmed up.
1.Start the engine and run at half throttle for 5 to 10 minutes to warm up. The engine must be warm before making the final settings. Check that the throttle and choke plates can fully open.
2.Idle Speed Setting: Place the throttle control into the “idle” or “slow” position. Set the low idle speed to 1200 rpm (± 75 rpm) by turning the low idle speed adjusting screw in or out. Check the speed using a tachometer (See Figure 17).
LOW IDLE SPEED
ADJUSTMENT SCREW
LOW IDLE FUEL
ADJUSTMENT NEEDLE
Figure 17
NOTE
The recommended low idle speed for basic engines is 1200 rpm. To ensure best results when setting the low idle fuel needle, the low idle speed must not exceed 1500 rpm.
CAUTION
The tip of the low idle fuel adjusting needle is tapered to critical dimensions. Damage to the needle and the seat in the carburetor body will result if the needle is forced.
3.Low Idle Fuel Needle Setting: Place the throttle into the “idle” or “slow” position. Turn the low idle fuel adjusting needle out (counterclockwise) slowly from the preliminary setting until the engine speed decreases (rich). Note the position of the needle.
Now turn the adjusting needle in (the engine speed will initially increase) until the engine speed decreases (lean). Note the position of the needle.
Set the adjusting needle midway between the rich and lean settings by backing out the needle approximately 1/8 to 1/4 turn (See Figure 18).
ADJUSTMENT LEAN
TO MIDPOINT
RICH
Figure 18
4.Recheck the idle speed using a tachometer. Readjust the speed to the tractor specification.
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