Speed boost
Press [Clutch] while holding [Gas].
More distance on jumps
Hold [A] then release it when you just jump off the ramp.
Turning
Press [Brake] while turning. This will create a tighter turn radius. When turning, release "Gas", then press "Gas" again. This will also create a tighter turn radius.
Tricks
Can-Can: Press [Y]x2.
Nac-Nac: Press [B]x2.
Heel Clicker: Press [Right] + [B].
Double Grab Heart Attack: Press [Right] + [Y].
Indian Air: Press [Left] + [B].
Cordova: Press [Left] + [Y].
Superman: Press [Down] + [B].
Lazy Boy: Press [Down] + [Y].
Fender Grab: Press [Up] + [B].
Bar Hop: Press [Up] + [Y].