Go into the option that lets you build your own track. start out by placing an "M" from the list of obstacles. An "M" looks like a little arrow and it cools the bike down. now skip about 2 spaces and place another "M" Keep doing that until you have about 10 in a row. Right at the end of the string of "M"s place an "H" jump. An "H" jump is the steepest one. Now just repeat the process until you fill-up the whole track with a space of "M"s and then an "H". You should end up with about 6 or 7 "H"s and a whole lot of "M"s. Now test the track by yourself. Hold down the "B" button and DON'T EVER LET GO! Also, hold right on the control pad. Keep holding right until you have gone over the first "H" jump and keep holding right until 1 millisecond before you hit the ground. As soon as you are about to hit the ground, tap left and then go back to forward. Your bike should bounce on the front wheel but not crash. Do the same thing off the next jump and the next and the next. If you do it right the sound of your bike will stall out and you will go faster, and faster, and faster! Eventually you will jump so high that you will go right through the top of the screen and come up on the bottom again. When you go through the screen make sure you hold back a little so you don't crash.
Continually change lanes to cut your opponents up and get ahead.
Keep a half-wheelie for 5 seconds at a time every 30 seconds. If successful you will speed up without falling over.
Turbo When Crashed
When you crash, your biker normally takes what feels like forever to get back on his bike. To speed him up, though, you can keep pressing the B button and he'll move more quickly.