How do you rebuild a carburetor?

The kit comes with the parts that wear out and usually need replacing. You just need to buy the kit. Make sure you get the "premium" kit (if available) because it is more complete. You will need some carb cleaner, available from auto parts stores, to soak parts in. Carburetor build-up can be stubborn to remove and soaking is the best way to ensure parts are clean. Soak overnight as a minimum, but it could require a few days before coming thoroughly clean, depending on the condition of the carb. Follow the step-by-step instructions in the rebuild kit CAREFULLY.
The carburetor needs to be removed. In a well ventilated area disassemble the carburetor. Taking photos may help with reassembly. Carefully match up the new and old parts in the rebuild kit, as some kits fit several models and contain extra parts. Clean all of the old parts to reused, and reassemble the carburetor.