Choose options from the main menu, then select cheat codes and enter the following passwords for the desired cheats:

•  STUPERCROSS -Unlock supercross tracks.
• ECONATION – Unlock national tracks.
• SWAPPIN – Unlock pro physics option at the setup menu before a race.
• OBTGOFAST – expert Al
• SQUIRRELDOG – Unlock 50cc bikes.
• BIGDOGS – Unlock 500cc bikes.
• CLAPPEDOUT – Complete career.