All tracks
 
 At the mode selection screen, press Up, Left, Right, L, Z, R. If you
 entered the code correctly, you will hear a sound.
 
 All bikes
 
 At the mode selection screen, press Up, Left, Right, L, Z, R, Up,
 Down, Down, Z, Down. If you entered the code correctly, you will hear
 a sound. 
 
 Game Shark Codez:
                     
 Infinite Nitros  
 810B8E4C 42C8
                     
 Unlock All Bikes 
 810FBCBE FFFF