Hi Ron and Ian,
My bike is an 800cc.
The following clears up the situation but does not explain why BMW took the strange decision to alter the engine size in a popular model, but not change the name, so causing real confusion.  Hope this is OK in the Triumph thread, but thats where it was raised, if mods wish to move to BMW, thats fine.
Produced from 2000 to 2007, the BMW F650GS is a 
dual-purpose motorcycle. It sold over 105,000 units during its production life.
In late 2006, the G series of offroad based motorcycles was launched  using the same 652 cc engine fitted to the F650GS, although that engine  is no longer manufactured by Rotax. Models include the Xcountry  (Scrambler), the Xchallenge (Enduro), and the Xmoto (supermoto).
In 2008, the single cylinder F650GS was discontinued and replaced by  an all-new design featuring a 798 cc, parallel twin engine. Intended as a  new-generation replacement for the old bikes, the new motorcycle has  retained the same F650GS model name, despite the fact that it has a  larger engine.
 
In late 2008, BMW relaunched the original single-cylinder F650GS  under the new name G650GS in the United States, South America, Greece[1] and Australia.[4][6]  The new G650GS is essentially the 2007 single-cylinder F650GS brought  back into production with some minor modifications and with the engine  assembled by Loncin in China instead of Rotax in Austria, but still using parts manufactured by Rotax in Europe. The finished engines are shipped back to BMW in Germany where the bikes  are assembled. G650GS models with the Chinese-assembled engines can be  easily identified as the engines are painted black while in the earlier  European-assembled engines were finished in silver. For a short period  prior to discontinuation of the bike in 2007 the engines were assembled  by Kymco in Taiwan. 
The G650GS received some upgrades over the F650GS of 2007: the engine  now produces 3 additional horsepower (now 53 hp) and received a  stronger 400 watt alternator.In the United States and Australia, ABS and heated grips are now standard equipment instead of additional cost options
 In 2010, at the 
EICMA  show in Italy, BMW Motorrad announced the global availability of the  G650GS with a slightly down-rated engine producing 35 kW (47 hp).
 
So the G650GS now available in the Chiang Mai  Barcelona showroom, has the Chinese made engine, which has been downrated to 47HP to allow sales to learners, who in some countries are restricted to bikes below 50HP. They have also changed the look, of fender and lights etc to resemble its bigger F800GS brother. They have cut a few Kg from the bike, and in doing so they may have reduced the specification of some parts. The bike has been visually upgraded, but I am not sure the other changes are an upgrade. In fact in the UK the bike costs 5,000UKP,  less than 300K Baht, and is cheaper than the Versys.