In order to fit and remove the handlebar of your R1200GS (2004-2007) you will need the Torx E10 for 1/2" or 1/4" drive made of high-quality chrome vanadium steel. For the R1200GS 2008-2012 & R1200GS Adventure 2008-2013 you will need the Torx E10 and E12.
You will need a special small and long wrench socket size...
High-quality Allen keys made of chrome-vanadium-steel are...
A correct and proper synchronisation of the carburettor or...