To stop a carburetor fire, the first step is to turn off the engine. This will cut off the fuel supply and prevent the fire from spreading. Once the engine is off, you can use a fire extinguisher to put out the flames. If you do not have a fire extinguisher, you can try to smother the flames with a wet cloth or blanket. Be sure to use caution when doing this, as the fire may be hot and can cause burns.
Once the fire is out, it is important to identify the cause and take steps to prevent it from happening again. This may involve cleaning the carburetor, replacing faulty parts, or adjusting the fuel mixture. It is also a good idea to have your carburetor inspected regularly by a qualified mechanic to ensure that it is in good condition and functioning properly.