The carburetor has the job of blending the air and fuel together in the right ratio to achieve combustion. Fuel that sits for a long period of time can gum up the inside of a carburetor, which will restrict the flow of fuel, resulting in an engine that is burning too lean. This can trigger a misfire. You can disassemble the carburetor and clean the internal parts on the inside or purchase a carburetor kit and replace all the internal parts, restoring your carburetor to optimal performance.
To start, remove the air filter housing and air filter, then remove the bolts holding down the carburetor and gasket. Next, pinch off the fuel line to prevent a fuel spill. Remove the fuel lines by twisting them and pulling them off. Next, remove the carburetor and disconnect the linkage. Start disassembly by removing the nut on the bowl, then remove the bowl...
The carburetor has the job of blending the air and fuel together in the right ratio to achieve combustion. Fuel that sits for a long period of time can gum up the inside of a carburetor, which will restrict the flow of fuel, resulting in an engine that is burning too lean. This can trigger a misfire. You can disassemble the carburetor and clean the internal parts on the inside or purchase a carburetor kit and replace all the internal parts, restoring your carburetor to optimal performance.
To start, remove the air filter housing and air filter, then remove the bolts holding down the carburetor and gasket. Next, pinch off the fuel line to prevent a fuel spill. Remove the fuel lines by twisting them and pulling them off. Next, remove the carburetor and disconnect the linkage. Start disassembly by removing the nut on the bowl, then remove the bowl and gasket. Next, remove the float pin and the needle valve. Unscrew the main jet screw and dump it out with the emulsion tube, then remove the plastic throttle stop and the metering plug from the carburetor. Spray the carburetor, fuel bowl, and all the small orifices with carburetor cleaner, then wipe clean. If you notice any corrosion inside the carburetor or the bowl, that is a sign the carburetor needs to be replaced.
Reinstall the new emulsion tube and new main jet and tighten. Install the new metering plug tightly, and reinstall the throttle stop screw, threading it in until it sticks out the other side about 1/16 of an inch. Next, install the new spring on the needle valve. Snap the new needle valve into the new float and reattach the float into the carburetor by sliding the new pin in. Install the new bowl O-ring, and reinstall the bowl and tighten down. Reinstall the carburetor with a new intake gasket back onto the engine, reattach the linkage and fuel line, remembering to un-pinch the fuel line. Reassemble the air filter housing with the air filter back onto the engine.
Next, you have to adjust the carburetor settings. Locate both idle screws on carburetor, one marked L (low) and one marked H (high). Turn both screws in to shut off fuel, then back off two turns. Next, start engine; it may not run well, these settings should allow it to start. Let it idle for a few minutes to get it to the right temperature for operation. Start by turning the L screw clockwise until the engine starts to slow, then turn it in the opposite direction until it once again starts to slow, then bring it to the midpoint of these two spots. Using a tachometer to gauge engine speed, set the idle speed screw to bring the engine to 1750 RPM for aluminum-cylinder engine or 1200 RPM for an engine with a cast-iron cylinder sleeve. At full throttle, turn the high speed or main jet screw clockwise until the engine begins to slow. Then, turn the screw the other way until the engine begins to slow. Turn the screw back to the midpoint. Once adjusted, check the engine acceleration by moving the throttle from idle to fast. The engine should accelerate smoothly. If necessary readjust mixture screws.
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