Fuel Mixture fuel ratio



hi all. was wondering about fuel ratio. im planning on taking a long ride . so i know ill run out of gas so for a two liter tank the usual gas tank for the chinese 48 cc . how much oil will i need at a ratio of 25 to 1 to put in the tank when i fill up at the gas station . will be on the road to do this so need to know how much oil to bring with me on my ride. lary ca