Assuming you already cranked down the screws that hold the carb top to the body/float chamber (not too much or you'll strip the threads), try checking total ignition advance above about 3000 RPM and make sure it matches the specification for your engine.
If you haven't rebuilt a carb before, I'd recommend taking it apart on a clean, flat surface liek a table or bench top with nothing else around the working area or on the floor near it. Make sure there's plenty of light on the subject while you work. Disassemble it on top of a clean towel so parts (check balls, especially) don't roll away and get lost. Make notes and sketch a drawing or take a digital photo BEFORE you take each assembly completely apart. The instructions are usually very good but, if you've never done one before, there's nothing like seeing what YOUR carb looked like before you ripped it to pieces.
Good luck!
