Road rash 64

Scooters:
Press C-Down, C-Right, C-Up, C-Left, Z(2), L, C-Left at the menu screen.

Super fast bikes:
Press C-Up, C-Left(2), C-Right, L, R, C-Down, Z at the menu screen.

Level 2:
Press R, C-Right, Z, R, L, C-Up, C-Left, C-Up at the menuscreen.
Level 3:
Press R, C-Right(3), R, C-Left, C-Down, Z at the menu screen.
Level 4:
Press R, C-Right, C-Down, C-Left, C-Right(2), Z, L at the menu screen.
Level 5:
Press Z, C-Right, C-Down, C-Left, C-Right(2), Z, L at the menu screen.