25:1 - You answered your own question!!!!
It depends on the 2 Stroke oil.
Mix mineral oil at 25:1
Mix Semi-Synthetic oil at 32:1
Mix Synthetic oil at 50:1
Go to Homebase or B&Q and buy a Mixing Bottle
to make it easier to get the correct ratio or call
ALM Manufacturing 01423 797208 for advice
Richard, July 2009