3/32" and 1/8" ID is pretty much standard with nothing larger required for even the larger engines. Some companies refer to the first size as med. and the second as large. Buy whichever one fits your fuel fittings the best. Be sure all fittings are barbed and use a positive means of retaining the line on the fitting such as a small clamp, lightly twisted wire or small nylon ty-wrap behind the barb.