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Playstation 2 - Jeremy McGraths Supercross World cheats

Infinite turbo
Press R2, L1, Square, Circle, Circle, Circle in the main menu.

Moon gravity
Press Up, Up, Up, Up, R1, Square, Circle in the main menu.

Unlock every bikes
Finish the hardcore part of career mode

Ride on front wheel:
Hold L2 + Square at a good speed

Wheelie:
Press L2 and give the bike gas.

Moves: 
Cliffhanger: Hold L2 + R2 and press Left, Right, Up.
Crack-Nac (Left): Hold L2 + R2 and press Down, Left.
Crack-Nac (Right): Hold L2 + R2 and press Down, Right.
Heart Attack: Hold L2 + R2 and press Left, Up, Down.
Indian Air: Hold L2 + R2 and press Left, Down. 
No Hands: Hold L2 + R2 and press Up, Down. 
Nothing: Hold L2 + R2 and press Down, Up. 
Switchblade (Left): Hold L2 + R2 and press Right, Left, Left.
Switchblade (Right): Hold L2 + R2 and press Left, Right, Right. 

Quick start:
Start your engine when the pre-race countdown reaches "3", then 
hold R2 when it reaches "1".