I am new to the forum and would like to ask a question, any help would be greatly appreciated.
Three days ago I purchased a used 2002 Sportster. It only had 2500 miles and the guy I got it from let it sit for a good while without cranking. I new this going in but figured it would be a nice project and after fixing I would appreciate the bike more. At first, when I was at his house to buy it, the seller told me that there is an issue with the carburetor because upon trying to start it, it would only crank with the choke out and after putting the choke in it would shut off and fuel would drain out of a tube underneath the motorcycle. So, after getting the bike home on trailer, I called a mechanic and he came to my house. He said the float was stuck and the carburetor may have issues. After he tore apart the carburetor, he used a rebuild kit with gaskets to put back in also he replaced the two jets, 1 45 and a 170. After he did the work, finally the bike would run with the choke in and upon driving I noticed that when ever I turned the throttle hard, the motorcycle would spit and sputter and hesitate. I called the mechanic back, he came over again, and after takin the carb back out he turned the screw for fuel/air on the back of the carb itself. Now the motorcycle will idle fine but the second you even touch the gas it cuts off, even a millimeter it seems. Also it will sometimes backfire out of the carb when cutting off and black smoke comes from the pipes. It does have fresh gas in it, but we are stumped completely, new jets rebuild and cleaned carb, what the heck is going on? I did notice that the throttle cable where it goes around the gold arm on the carb seems a tad bit loose? But i just don't know what this could be. The day it was up and running decent, I remember, when I held the throttle full it would spit and sputter now I cant even touch the throttle or it dies off all the way/please help I have already spent enough money with him I should have just taken it to Harley

 

Take the air cleaner off, give the throttle a slight twist and make sure you see a stream of fuel squirt out of the accelerator jet into the carb throat. If not, then the accelerator pump may have a torn diaphragm

 

clean the carb soak it it prolly has gunk in it still,