Jet Moto Cheats (PlayStation)

On the options screen change the difficulty to Amateur, turn off turbos, and turn off
grapples. Now select Credits while holding
  L2 on the controller.

At the "Code Enabled" screen (see Easier Tricks) press Square, L1, Triangle, Right, L1,
Down, R2, Triangle.

At the Options Menu press Down, Up, X, Triangle, Square.

Go to Cliff Diver Track. Near the end of the track there is a tall island with a tree on
it. Ride up to the tree and turbo off the
  island. If your timing is good you'll be able to do between 4 and 8 flips!

First, unlock CliffDiver, then go to the island that is on the straightaway to the Start
checkpoint. You can get up the island by pushing down and throttle. You will slowly acsend
to the top, when you get there, back up as far as you can without falling down. On the
top, press turbo, you will fly off the island into the air, if you are good, you might be
able to pull off three complete flips, and will get a lot of applause. happy flipping!

In the black water fall level you can go in the house by raming the door.

On the options screen change the difficulty to Amateur, turn off turbos, and turn off
grapples. Now select Credits while holding
  L1 on the controller. You can change pictures by pressing X or cancel by pressing
Triangle.

In Suicide Swamp, on the dirt trail that has the grapple at the end, where the circle
bends at the top, thre are 3 signs, 2 Nestle
  & 1 Butterfinger, line yourself up with one of these signs, then hit your turbo
& crash through the sign, it you've done this
  correctly you will be in an area where there is nothing but water & you can take a
fun trip all over the place, but be careful
  about when you come back, if you aren't in the right spot, the track will send you
flying & screaming.

In the joyride track, goto the easy bridge to do stunts. after going on it turn around and
go towards the backside of it. aim for
  the left edge of the underside. U WILL go through it, but it shoots u up super high in
the air. U can get douple flips and
  corkscrews with it. with super easy stunt enabled, U can do 4/5 flips/corkscrews!! It's
COOL check it out.

On Joyride, go to the ramp (not the broken highway). Jump off the ramp and turn around. Go
towards the side of the ramp and
  go to the first line that appears on the ramp. Slowly ride up to it and right when you
hit it will send you flying. While in the air
  you can do three backflips with three twists if you press and hold L1 or R1 and Up or
Down.

  Alternatively, go to the first ramp (not the broken highway) and gain as much speed as
possible. Once you're on the ramp, pull
  off on the side with the black line. This takes practice, but if you get it right you'll
sail over the bouys and can drive around
  outside.

On the CLIFFDIVER stage, go to the big rock after you have made the dive from the cliff.
Go infront of the rock and press
  down, then quickly press and hold the accelerate button. When you start to climb up,
press turbo and you will be on your way
  to do stunts in the air for a very long time.

The only codes I know of for Jet Moto can only be used *after* you've beat a season with
all the tracks on the hardest setting.
  But if you want them, they are:

  Super Agility: down,O,left,L1,left,right,left,right. (this lets you pull tricks quick
and easy) 
  Zero Resistance: square,L1,triangle,right,L1,down,R2,triangle 
  Double Stunt Points: right,up,O,L2,triangle,O,R1,R2 (the name says it all) 
  Show off camera enabled: triangle,down,square,triangle,L1,L1,R1,R1 (this really
sucks,try it) 
  Air Brakes: R1,R2,right,L2,up,O,up,O (very handy avoiding air wrecks) 
  Rocket Racer-triangle,up,up,L2,L2,up,up,up (makes you run turbo 
  speed all the time,you'll be winning cypruss track by 30 seconds with the right racer,it
rocks!!!) 
  Unlimited Turbos: triangle,O,right,R2,up,square,up,triangle 
  (not much use but for acceleration with rocket code) 
  Ice Racing: up,R2,R1,right,L1,square,right,right (makes everything slippery as ice,very
hard)

To get all the tracks without beating the season, goto the options screen, set the
difficulty to amateur and the trophy presenter
  to male. then go back to the main screen by pressing start and enter in the following
code: U, R,D,L,U,R,D,L go back to the
  options screen by going left once and pressing X. set the difficulty to prof. and the
trophy presenter to riders choice. then hit
  start to go back to the main screen. now enter in the following: U,L,D,R,U,L,D,R you
will then here a noise to signify that it
  worked.

To enable codes instead of beating the game.

  First go to the options screen. Then put the diffulty to professional, and put the
number of laps to 6. Then go back to the title
  srceen. Then press circle, circle, circle, square, triangle, triangle, square, triangle.
You will hear a sound and it will have a ballon
  displaying "Codes Enabled".