Open to all riders from the year of their 16th birthday. Open to both air-cooled and water-cooled engines with a capacity of no greater than 50cc. Carburettor shall be no greater than 21mm. Any production reeds, air box, clutch, wheels, tires (with or without pattern). Brake levers may be switched from their factory fitted side, but front and rear brakes must operate independently of each other and no single lever may control more than one brake disk.