I was very much in doubt if I should include this chapter or not, because every indication given on the expected lifetime of specific parts will at best be extremely unprecise. You will probably discover great differences form this chart because owners does not treat their bikes the same way and drive under different conditions.
But anyway - here's my best shot.
||50.000 km with velocity stacks, significantly more with filters.
||At least 3 changes of piston rings if its the cylinders with Nikasil plating in the bores (Gillardoni). Most are.
|connection rod bearing shells
||In any engine this is the bearing with the most load on it. Change it at 80.000 to play it safe. Failures on this bearing can be a real disaster for your engine.
||100.000 km. Very much depending on user
|Crown wheel/pinion in rear drive bevel box
|Unijunction in drive shaft
There's lots of other parts in the engine where I never heard anyone dare to guess at a expected lifetime, and I'll once more state that the figures above are very, very rough estimates.