Accelerate while doing a wheelie, and press either down or d key to charge a boost. Your will be able to still drive at full speed while charging a boost. Note: This tech works in the games: "Moto X3M", "Moto X3M Winter", "Moto X3M Pool Party", "Moto X3M Spooky Land", "Moto X3M 2", and "Moto X3M 3".
Moto X3M has 22 levels, each more action-packed than the last. Each level includes several checkpoints, along with loops, turns, high-flying jumps, and opportunities to do plenty of flips and tricks.