Go through single player Nationals, and earn the Mils Mesas environment or enough points to purchase it. After getting this map, exit the mode that you are in, and go to single player. Choose the custom event option, then go to "Nationals". Select the Mils Mesas track. Set the play mode to "Single Play", laps to "10", and number of opponents to "0". The MX superclass vehicle is recommended, but you can use an ATV or normal MX. Start the race, and do not worry about time or anything else. Just do as many tricks as possible. Try Dingo Backflips+ and 360+ for quick points. You can get about 700,000 score points and 350,000 store points.
Stationary wheelie
Go to "Single Player Custom Event", then select "Freestyle" followed by "Ski Jump". You will be given a choice of two tracks. Select the second one. When you go down the ski jump, pop a wheelie then hold it. Somewhere near the center of the ski jump you should just remain there until you stop popping a wheelie.
Various Codes
At the options menu, select the "Cheat Codes" option, then enter one of the following codes to activate the corresponding cheat function. If you entered the code correctly, you will hear the sound of an engine.
1 million store points
Enter "MANYZEROS" as a code.
50cc bike class
Enter "LITTLEGUY" as a code to unlock 50cc bike class.
All bikes
Enter "ONRAILS" as a code to unlock all bikes.
All bonuses
Enter "YOUGOTIT" as a code to unlock all bonuses.
All challenges
Enter "MORESTUFF" as a code to unlock all challenges.
All gear
Enter "WELLDRESSED" as a code to unlock all gear.
All machines
Enter "MCREWHEELS" as a code to unlock all machines.
All riders
Enter "WHOSTHAT" as a code to unlock all riders.
All tracks
Enter "FREETICKET" as a code to unlock all tracks.
Freestyle tracks
Enter "ALLSTYLE" as a code to unlock Freestyle tracks.
Paralyzer Monster Truck
Enter "PWNAGE" as a code to unlock the Paralyzer Monster Truck.