An air filter for a combustion engine for off-load motorcycles is made from a porous foam material. The air filter has contiguous side surface forming a cavity with at least two openings where the side surface contains at least one filter layer, a bottom surface closing at least one of the two openings where the bottom surface contains at least one filter layer, where the side surface has more air resistant than the bottom surface. The side surface has more air resistant than said bottom surface by arranging any combination of thickness of the surfaces, number of layers, and porosity ratio of the layers.