This step is pretty easy. For this, I just used my razor but a drill will probably work just as well and quicker. Using the razor, I found the center, and while applying pressure, I just twisted the razor in circles. It slowly shaved a hole though the metal. After the hole is created, there will probably be sharp metal bits around the hole's edge. Simply use a file (I used the back end of the razor which is metal. A coin would work for this too.) and smooth out the edge. The carb is now set to go.