Im running a 2003 twin spark 1150gs 28k on clock. Its been running well, apart from last week, it doesnt seem to pull well in high revs and seems to be a bit juttery in high revs too. any ideas or is it back to BMW technitians.
Check the main coil caps, they have a high failure rate and give the symptoms you describe -
pull off the lower secondary plug caps and see how it runs on just the main plugs.
If it runs on just one side re-attach the lower plug on that side and it should then run normally to confirm it's the main plug ( it could aslo be both sides failed).
Simple replacement ( but expensive) just unclip the old one and reclip the new one.
I'm suffering from similar symptons on a 30k 1150 adv. I have checked and changed everything possible but it still lacks power and runs rough. Today I checked the compression of both pots with a Snap On guage and only got 115 on both cylinders.
4000 miles in Morocco? Bores or Valve seats? No excessive oil consumption.
Smiffy, being a simpleton at heart, and in mind, I would suspect the valves first...clearances rather than burned out. I check the easy things first and work up - usually does the trick.
I think the bores are nickasil, so should last for 100s of 000s of miles, provided the rings get some slippery stuff and you don't wash it all off with evaporating stuff by running it too rich.