China Border crossing
After my attempt to find any information on the chinese border crossing (that is recent), i decided to post some info which might be helpful.
I went to the chinese embassy in Istanbul... and to be honest they didnt seem to know much. But the guy took a long time in the back office, and he said, as others have said, that it is possible, but i need to go to a chinese travel agency, and they need to get special permission from the chinese tourism bureau or something. He said it uisually takes up to 3 months... and i have no idea of the costs. So for me, that was out of the question, and i am going to UAE instead.
However, ialso met a new zealand man who had done the reverse trip, from China to Turkey. He bought his bike in kyrgistan. He said that both Tajikstan and Kyrgstan are hubs for selling buying bikes (cheaper ones that is). He bought his bike for 400 us dollars. So if you are driving a long on a budget (with a bike that doesnt cost over 1500 euros i guess)... you can probably sell it there and continue to china. He said can also buy a 125 across the border, in china.
It;s not much info, but its better than nothing... and it would have helped me!