Remove the top cover from the carb.
Ty-wrap or tape the throttle lever wide open.
Take a 2.5MM Allen wrench or T-Handle and loosen the hook shaped retainer that holds the needle down.
Take either a strong pen-magnet or needle nose plier and pull the needle straight up.
Do not lose the plastic washer that is below the e-clip.
Take off the plastic washer.
Push the opening of the e-clip down on a flat surface with your thumb or finger on top of the clip so that it doesnt go flying.
The needle numbers are from the top down (1-5 normally).
Place the e-clip in the desired postion and push it on.
Re-install making sure plastic washer is in place and J-hook slides over the needle as you tighten it.
PS if there are any odd needle postions like 3.5 you need to add a shim washer between the existing plastic washer and the e-clip. Your dealer or other vendor like SLP can get you the shim washers.
Good luck,
Steve