Main air jet

Hey I just got a Factory Pro jet kit and advancer for my 2000 ZX9r and I'm in the process of fiiting them both. All is good except the jet kit requires me to drill out the main air jet and I'm not sure where it is
As i dont want to screw this up can anyone tell me where this main air jet is or explain it in a way that I can work it out myself? I'm pretty sure its in the bellmouth on the filter side of the carb and is linked to the main jet but some more info is required before I go drilling willy nilly 

