The high temperatures may have something to do with it? Although only very small individually, the differences between riding in 35C hot and 15C temperature climates all adds up:

• Tyres for create more rolling resistance when hot.
  
• Thermal expansion of petrol; you get less KJ of energy per litre in a hot climate than you do in a cold one. Won't make a massive difference, but a difference none the less!
  
• The XT doesn't have a fuel temperature sensor in the fuel rail, so cannot compensate for warmer fuel being delivered from the tank. It is metered by volume, not mass/energy.
  
• Loss of fuel through evaporation and/or expansion from the tank as it's vented to atmosphere. It has come to light in another thread recently that the ABS Ten, due to the shape of it's tank and different breather to the standard bike, can spill fuel out of the breather hose if left in direct sunshine for any length of time even with a part filled tank.
  
• Air is less dense, and although the bike's sensors (MAP/AIT) compensate to a degree, it'll still make a difference.
  
• The fan will operate more often, putting additional load on the alternator and therefore the engine. Again only a very tiny increase in drag, but added to everything else above will compound matters, as will the fact that resistance in all the bike's electrical circuits will increase with temperature!

What fuel are you putting in it at the moment? 91RON, 95RON, 98RON, E5, E10? It all makes a slight difference to economy, especially the ethanol content.

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