thats just a back fire. it is because your oil injector gives to much oil fouling an old plug. nothing you can do about it but remove it and premix or change your spark plug.
when change your spark plug and it should run great. (local auto parts store less than 5 bucks for a spark plug). my guess any way. a spark plug is incredibly easy to change (unless if its cross threaded aheemmmm me) unsrew spark plug with thing that you can get it to unscrew with. i use a 13/16 inches but that's the wrong size it is like 20-22 mm metric., treats spark plug tool works.
if it isn't that
your carb is pretty easy to take apart do not take it to Suzuki. if you are rich and want to blow money take it to a local moped shop. they know mopeds and they will probably be cheaper. if you don't have one near you. it is a 14m nut for the choke pull the 2 fuel lines ,remeber their order, a twisty cap throttle slide, just use your hand, 2 10 mm bolts both aren't easy to get at but the whole thing shouldn't take ore than 30 min for taking it off. then 4 philips head screw on the bottom of the bowl and tahda. then blow through all the holes with air.
sadly i can do that about as fast as it took to type this.