What is the purpose of a carburetor valve or as it is referred as a sleeve s***w in a user manual?

Question

This is what it looks like:

http://www.minibikepartsnow.com/partspage/carburetor-valve.htm

Answer 1

Looks to me like this is a fuel shut off valve.  Usually located under the gas tank and has a hose to the carb. inlet. The valve is turned off when the bike sits overnight or for a long period of time . This is so the carb. wont flood and fuel will enter the engine.  Hope this helps