Moto3 uses 250cc engines under the class introduced in 2012.
Moto3 replaced the 125cc two-stroke Grand Prix class in 2012. The new category adopted four-stroke single-cylinder engines with a maximum displacement of 250cc, creating a lighter and more modern entry point to the world championship. The class was intended to reduce costs while encouraging multiple manufacturers and independent teams.
The 250cc limit is a maximum capacity, not a claim that every engine has identical performance. Manufacturers develop their own engines within the technical rules, and teams compete with different chassis designs. Moto3 motorcycles are notably smaller and less powerful than Moto2’s 765cc machines and MotoGP’s prototype bikes.
A frequent mix-up is treating Moto3 as a continuation of the old 125cc class because both occupy the lightweight category. The class changed both engine technology and displacement in 2012: four-stroke 250cc engines replaced two-stroke 125cc power units.