Things You'll Need
Berryman Chem-Dip cleaner
Correct carburetor rebuild kit
SAE wrench set
Metric wrench set
Compressed air and blow nozzle
The Snapper lawnmower was one of the first rotary lawnmowers which rolled out in 1951. The two most common carburetors seen in the Snapper mowers since about 1990 are the Briggs & Stratton and the Tecumseh. Since Briggs & Stratton has owned Snapper since 2004, the engines since that time are Briggs & Stratton. The rebuild process is basically identical for the Tecumseh and Briggs and Stratton carburetors; however, there are significant differences in each model and internal porting of two brands of carburetors.
Carburetor Disassembly and Cleaning
Put on safety glasses and nitrile gloves. Remove the fuel line. Remove the two bolts that attach the carburetor to the manifold. Carefully disengage the throttle and governor linkages. Make note of which hole each linkage is inserted. Remove the rubber-connected crankcase ventilation tube.
Remove the bowl nut, and high speed adjustment needle, if equipped, with an appropriate-sized wrench. Remove the bowl and pour out the old fuel in a discard container. Turn the carburetor upside down and remove the float pin. Carefully remove the needle spring, needle and float assembly.
Remove the main jet from inside the bowl tube either with a screwdriver or by pressing it out from inside the throat and through the bowl tube. Remove the idle needle-valve and spring, with a screwdriver, if equipped. Remove any Welch plugs with a small, sharp punch. Remove the filter screen, if present. Carefully, remove the needle seat gasket with a pick, if present.
Soak the main components in carburetor cleaner for 30 minutes. Using compressed air and a blow nozzle, dry off the components and clear all passages. Use a toothpick to remove any stubborn debris. If there is rust in the bottom of the bowl, use sandpaper to remove and resoak in carburetor cleaner.
Reassembly and Installation
Reinstall the new Welch plugs with a blunt punch. Install new O-rings or gaskets on the main jet. Press or screw in the main jet until firmly seated. Reinstall the cleaned filter screen. Install a new needle seat gasket.
Reinstall the float assembly. Insert the float hinge pin into the holder. Turn the carburetor upside-down and measure the float high. Adjust, to the particular carburetor specification, by carefully bending the metal tab on the hinge. Do not push pressure against the needle and seat. Install a new bowl gasket and replace the bowl and bowl nut. Tighten the bowl nut.
Replace the idle needle valve and spring, if equipped. To bench adjust, turn the idle needle-valve until lightly seated, then back out one and one-half turns. If equipped, adjust the high-speed needle using the same procedure.
Connect the governor and throttle linkages to the carburetor. Install the carburetor on the intake manifold with a new gasket. Tighten the two bolts. Install the crankcase ventilation tube and the fuel line.
Start the engine and let it run and warm up a little. If an idle adjustment screw is present, set the throttle at idle and turn the idle adjustment screw clockwise until the engine is just about to stall. Then, turn the idle adjustment screw counter-clockwise until the engine runs smoothly but is not racing. If a high-speed adjustment screw is present, set the throttle to high and turn the high-speed adjustment screw clockwise until the engine begins to misfire. Then, turn the screw counter-clockwise until maximum, smooth engine speed is obtained.
Most Tecumseh carburetors have plastic main jets that can be damaged by the cleaner and must be removed.
Always wear safety glasses. Gasoline and carburetor cleaners are a skin irritant,so always wear nitrile gloves when working with these fluids.