Racing Air Filter 50cc Size dia.: 35mm length: 68mm Works great on small 2 stroke and 4 stoke engines. After-Market Air Filter with a cool finish for 49c, 70cc, 90cc, 100cc, 110cc and 125cc Honda style 4-stroke engines. After-Market Performance. Air Filter for 50cc to 125cc 4-stroke engines commonly found on imported ATVs, Dirt Bikes, Karts, Super Pocket Bikes, Mini-Choppers and many more.