Originally Posted by norschweger
Today we stripped the girl and opened the engine. The machanic (KTM, but no experience with a bike like this) says the timing chain is that lose that the tensioner cannot tighten it enough (front cylinder) and that there was no leakage from the water pump (oil looked normal, but I could not communicate with him why he was so sure about excluding this probable failure just by opening the pump to the rotor).When turning over the engine there is a clic-sound at one point (seems to come from the valves (front cylinder). i hope tomorrow will bring more clarity and an inexpensive and fast solution...(they have already talked about three weeks for parts..., guess there must be a faster way from the States)
I would be very cautious at this point - everything else you have posted points to a leaking water pump seal. The tensioner is hydraulic (this why it clatters on start up and when the oil light flickers). You have said that the coolant is disappearing, where is it going? Also what has a loose cam chain got to do with low oil pressure.
Have a look at the oil filter and maybe post a pic-up. It is pretty apparent if there is water in the oil.