Remove Carburetor But Do Not Disassemble

4. Inspect intermediate adjustment needle and spring to see if spring coils are binding before needle seats. If needle does not seat grind a small amount of material from each end of spring. You can check to see if needle is seating by applying blue dye to needle taper and screwing down lightly into seat and noting mark on needle taper.

5. Check main nozzle ball check valve for leakage, as follows:

Seal one side of venturi with finger and apply alternate pressure and vacuum by mouth using grommet end of tool, Part No. 96960-68, seated in venturi as shown in Fig. 3F-7B.

Figure 3F-7B. Checking Main Nozzle Ball Check Valve for Leakage

Vacuum should release ball, and pressure should seat ball in nozzle assembly.

Figure 3F-7C. Removing Main Nozzle Welch Plug

If leakage is evident, carburetor must be disassembled and main nozzle check valve assembly replaced. To replace main nozzle, puncture welch plug with pointed tool, avoiding center, as shown in Fig. 3F-7C. Remove nozzle welch plug and use stepped end of punch, Part No. 96962-68, on nozzle, tapping it through into venturi using plastic hammer. See Fig. 3F-7D. Use larger end of tool to install the new check valve in the same manner. See Fig. 3F-7E.

Figure 3F-7D. Removing Main Nozzle

Figure 3F-7E. Installing Main Nozzle

6. Inspect idle needle and seat in carburetor bore for any distortion or a cracked casting.

7. Inspect choke relief disc (upper half of choke) for distortion or stress cracks at the area rotating on choke shaft.

DISASSEMBLY, INSPECTION AND REPLACEMENT OF PARTS

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