Hi go-rebels,
Drain the gas from the carburetor [ a small screw at the near the bottom of the float bowl], remove carburetor from cylinder. Remove phillips screws that hold the bowl onto the carburetor. The main jet is in the center, remove and replace. If the o-ring gets wet with gasoline you will need to shrink it before you can re-install the bowl. Put in sun or use a hair dryer to shrink o-ring. Re-install the bowl with the phillips screws. Attach the carburetor to cylinder. Done.
Have fun,