i have a yamahatw and i have cleaned the carburettor and the air filter but the spark plug still goes black. And it uses alot of fuel it was fuel to the brim i have done 11miles on it and it is have empty. How can i stop it from doing this.

try leaning off air fuel the mixture by turning the screw on your carb,not the idle screw the other one. just do it a 1/4 turn at a time . then run it for a day to assess if its any better . remember to make a note of where you started from,

cheers,ill try it