Mixing two stroke fuel is not rocket science. If your engine manufacturer requires a 50:1 mixture, you are not going to do any damage to your motor if you end up with, say, 45:1 or a 55:1 mixture. Having said that, this handy measuring cylinder with convenient ratio chart printed on the side will save you from getting the mixture critically wrong.
Remember to clean the remaining oil out by putting about 100-150ml of petrol in it, swirling it about and emptying it in to your fuel container. If you leave the container oily, you will end up with dead bugs in the cup!
