My 1981 xr100 leaks gas out of the bottom of the carburetor, and it bogs down while driving?

i have a 1981 xr100 that i just bought from the englishtown swap meet. on the way home we had to put it on its side, and now when i open the fuel valve gas poures out of this little hole on the bottom of the carb, and while driving it bogs down alot, it also wont idle. when i took the spark plug out it was really black, can anyone please help me... do i need a new carb or should i clean it or what???