Probably most ppl with 2-strokes don't carry extra fuel unless their going on an extended ride.What i used to do is carry an alcohol hip flask with me with a mixture of fuel & oil,enough diluted oil to make 1.5 litres of 2-stroke fuel.If i got low in fuel simply ride into a gas station,buy 1.5L straight fuel then tip the flask contents in....shake WELL.
There's also this...good for 2 & 4 strokes:
http://www.motoredbikes.com/showthread.php?t=19700