Hey Guys, give this a try. I got fromt he Yammie Forum from BrokemyBanshee. See if this works.

Perform the Ultimate
Hold 0 and press Up, Down, left and right on the direction pad while in the air to perform the "Ultimate" which is worth about 35,000 points.

Increase Difficulty
Enter ALLOUTAI at the name screen in the pro-career mode.

Ravage 1000 Quad and Alternate Riding Gear
Finish an entire pro-career.

Reveal (Yamaha) Raptor
Once you get the 1000cc bike after beating the game once. You must beat the game two more times with the special 1000cc bike. Then the RAPTOR will be revealed in the bike menu.

Get the CR500 Moto cross bike
Beat the game 4 times with the ravage eagle and it will be with the Honda Atvs in the bike selection. Smoke the ravage1000

Get Ricky Carmichael On A Kawasaki 250cc
Go to stadium SuperCross. Pick practice mode and the track called Syracuse. Pick a female rider. Then pick the thor gold gear. Next pick any quad. Complete 20 laps. Then hit pause. Hold L1 and press: Square, Square, Triangle, Square, Triangle, 0, 0, Triangle, X, X, Triangle. The screen should wiggle if done correctly.

Beat the computer every time
When playing the game press L1 ,L1 ,L1 .the computer will lose

Infinite Tricks
Go to Fort Roberts and find the G.I. training ground. When you get there find the three stair like bars in front of the X looking things. Get right in front of the small one and back up. Do a wheelie onto the small one. If you do it right your ATV will get caught on the middle log and and you can do as many tricks as you want, but be sure to keep your balance.
I don't have the game or PS2, but play it at my friends house all the time. Thanks BrokemyShee.

 

Has anyone tried this? Do they work??

 

There is now raptor in the game it was taken out right before the game was released thanks to yamaha I tried the ricky carmichael code and it didn't work.

 

tried the codes DO NOT WORK

 

Hey cman wanna go ridin sometime?

 

Infinite tricks works.