In Morocco, Libya and Sudan fully loaded was getting the same - 380-450km including almost all reserve doing 40-80km/h.
Friend on identical bike had wildly different consumption +-15%.
The things I noticed that made a significant difference included: speed obviously, needle settings in carb,condition and adjustment of chain/sprocket set, state of filter/airbox, quality of fuel and altitude. Was told tyres and tyre pressures also have an impact.
[This message has been edited by city2surf (edited 19 October 2004).]