I'm no BMW expert but if he didn't check the coolant level , I'll hazard a guess .
Sounds like a partial seizure due to lack of coolant/oil/overheating .
A rebore and new coolant pump and/or seals sounds in order .
Check the valves as well .
Originally Posted by R.Itchy
A friend of mine recently fell into a bit of bad luck with his 1999 F650. He was in Whitehorse NWT. when his engine overheat light came on, So he let it cool down, started it again and ran a little further, light came on again, so he let it cool down again and then started it up and got it to the nearset town. He said it lacked power and all he knows is the compression of the engine he is claiming is 60 psi.
As I work on my Harley he asked if I would look at his bike. I'm unfamiliar with BMW's Rotax engine, but with patience and a manual, I'm confident we can figure it out.
The bike has just over 70,000 kms on it and up until that point had performed flawlessly.
Blessed are the cracked, for they let in the light. - Spike Milligan
"When you come to a fork in the road ,take it ! When you come to a spoon in the road ,take that also ."