The thing is, the main jet that the bike shipped with is only the "safe" main jet anyway. The carburetion will need fine setting up not only once, but at every race (sometimes more than once per meeting too, if you are really competetive!) to make peak power.
What size is the current main jet? What type is it round or hex? The manual will probably list the main jet part number(s), so I doubt there is any reason why you could not get a replacement jet, or even a range of jets, by the weekend.
If you were to update your profile with your location, then maybe someone relatively local to you will offer some advice on sourcing the parts.
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Andy.
NSR-WORLD.COM
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