Craftsman 143.991200 Specifications download pdf (Page 17)

If further adjustment is required, the main adjustment should be made under a load condition.

If the engine stops or hesitates while engaging the load (lean), turn the main mixture adjusting screw out

(counterclockwise) 1/8 turn at a time, testing each setting with the equipment under load, until this condition is

corrected. A few Tecumseh carburetors were built as air adjust idle system. If you have one, the adjustments

are reversed out for lean in for richer.

If the engine smokes excessively (rich), turn the main adjusting screw in (clockwise) 1/8 turn at a time, testing

each setting with the equipment under load, until this condition is corrected.

After the main mixture screw is set, move the speed control to the IDLE or SLOW position. If the engine does

not idle smoothly, turn the idle mixture screw 1/8 turn either in (clockwise) or out (counterclockwise) until

engine idles smoothly.

Recheck the high and low R.P.M. setting and adjust as necessary.

CARBURETOR DISASSEMBLY PROCEDURE

NOTE : CARBURETORS THAT ARE EMISSION COMPLIANT (MANUFACTURING NUMBERS 5000 OR

GREATER) WITH FIXED IDLE OR MAIN JETS ARE TO BE REMOVED BY DEALERS ONLY FOR INSPECTION

AND CLEANING.

1. Note or mark the high and low mixture adjusting screws to aid in reassembly (if applicable). Remove

the high speed mixture screw, bowl nut, and float bowl. Remove the idle mixture screw assembly. On

Series 7 carburetors, release the wire retainer that retains the bowl and remove the bowl assembly. If

a screwdriver or similar tool is used to release the retainer, carefully move the retainer to prevent

bending of the wire.

2. Series 8 carburetors have a tamper resistant cap, over the fixed idle jet. (diag. 21). The cap is removed

by piercing it with an ice pick or similar instrument, then remove the jet for service, always replace the

cap.

3. Note the position of the spring clip on the inlet needle and float. Remove the float hinge pin with a

needlenose pliers. Some carburetors use a float dampening spring to aid the inlet valve to maintain a

steady position in rough service applications. Note the position of the hooks before removing the float

hinge pin (diag. 25). On Series 7 carburetors, grasp the crossbrace on the float with a needlenose

pliers and pull straight out to release the float hinge pin.

4. Remove the float, clip, and inlet needle.

5. Remove the inlet needle seat using a wire or a paper clip with a 3/32" (2.38 mm) hook end (Tecumseh

carburetors only, Walbro model LMK uses a non-serviceable seat). Push the hook through the hole in

the center of the seat and pull out to remove it.

6. On Series 7 only, remove the main nozzle tube, "O" ring, and spring located in the center leg of the

carburetor bowl. Remove the bowl drain screw and gasket. Remove the spring, metering jet, and "O"

ring.

7. Note or mark the action of the choke and throttle shutters and the hook points of the choke or throttle

return spring or seal retainer springs located on the top of the choke or throttle shaft.

NOTE: MARK THE EDGES OF THE THROTTLE AND CHOKE SHUTTERS PRIOR TO DISASSEMBLY.

THE SHUTTERS HAVE BEVELED EDGES AND MUST BE INSTALLED IN THE ORIGINAL POSITION.

Remove the throttle shutter, throttle shaft, choke shutter, springs and choke shaft by removing the

screw or screws that attach the throttle or choke shutter to the shaft inside the air horn. To remove the

choke shaft assembly on Series 7 or Walbro LMK carburetors, grasp the choke shutter with a pliers

and pull it through the slot in the choke shaft. Slide the choke shaft out of the carburetor body.

CHOKE

END

THROTTLE

END

LONG END

OF CLIP

CLIP

OPEN END

OF CLIP

3/32"

(2.38 mm)

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Craftsman 143.991200 Specifications Page 17

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