Everything is good now. I am ready to leave the Oasis.
The people from the Oasis took me to a very good mechanic shop here in Ulan Bator. His name is Ratna, and he used to work in Japan and he has contacts there to get parts. So besides having way less resources here in Mongolia, if you have a big bike stuck in Ulan Bator, it looks like the best place to go. Ratna even owns a 1200gs now. He just bought it. So they know it well.
ARKA MOTO SHOP
So the engine was stuck and it did not turn. Even after removing all the water. The mechanics started pulling out pieces to look what was preventing the engine to turn. Bent conrod was their first guess. But they were ok and they continued pulling out pieces until they got to the distribution system.
They stopped there for one day waiting for me to download some pages of the repair manual for the bike, they were in Spanish, but only looking at the pictures they figured out how to put the whole engine apart.
Finally they found a broken tooth in the flywheel. Which is a good thing. It probably broke when I tried to start the bike with water in the engine and by breaking it prevented something worse.
So once the failure was found, I had to decide between waiting for the part from Spain or Japan or just let them weld it. They suggested the welding solution and they seemed very confident on being able to do a good job.
I had a good feeling about them, since I saw them working all the time and to me it looked that they knew quite well what they where doing all the time. Also, I do believe that in these countries, people are much more resourceful that we in Europe or North America, where we just change the parts when things break.
The welding looked perfect and they put everything back together... and the bike sounds, feels and rides normal. So I guess it is problem solved.
The total cost of the reparation (4 days) was 276 euros. This would have costed 1700 euros in Spain. So I am quite happy.
However my original plan was to go to Magadan at the end of august but now I changed my mind and I am going to Japan through the Shakhalin island. Rescuing the bike from Magadan is way too expensive and I suspect that going to Magadan can be very boring and also if the weather is bad may be another mud madness with more water crossings and everything...
So I am expending the money I had planned to spend in bringing the bike Magadan - Vlad - South Corea - Vancouver in a Shakhalin - Japan - Vancouver instead.