Something is very off with that bike... First thing is to pull tank off and have a look at the carb... You can get at most carb wear items without removing the carb from the bike... First off pull the plastic cap off the top of the carb and remove the slide and inspect the diaphragm for defects... Have a look at your jet needle, make sure it has the metal washer on the bottom and the 2 plastic sandwich washers in place... The Jet needle sometimes will wear so much that it will break in 2... With a 17 mm wrench to unscrew the bowl plug you can then access the main jet with a right angle screwdriver and a bit of fiddling.. Take the main jet and the tube washer out and then you can pull the plastic slide guide up through the top of the carb... Inspect the slide guide for wear by looking at the wear indicator depressions on the slide running surface... Look at the needle jet{emulsion tube} to see if it has worn oval and check that the o-ring is in place on the bottom of the slide guide... All this can be done with the carb on the bike... also check the main jet #, it should be between 152.5 and 160, any larger than that usually causes an overly rich condition.. It has happened before where the pilot jet has rattled loose and found sitting in the bottom of the float bowl..

Like I mentioned before, issues with the fuel pump can also cause problems...