plug chops to confirm main jetting is correct:
http://www.blasterforum.com/threads/how-to-plug-chop.53237/
the slide in the carb has an adjustable needle that controls 1/4 - 3/4 throttle jetting as it slides up and down in the needle jet.
the stock setting is clip in the middle (3rd) slot position, certain pipes and very high or low temps and elevations are the only reason i know of that the clip should be moved to lower/raise the needle to richen/lean the needle jetting.
very rarely will a stock carb/engine need anything but the stock needle.
a proper, full cleaning of the carb should include removing the needle jet for cleaning of the small holes it has along it's sides.
cleaning and needle jetting/adjustment info here....
http://www.blasterforum.com/threads/how-to-clean-your-carbureutor.254/
http://www.blasterforum.com/threads/vid-on-changing-needle-clip-position.47758/