Barnaul felt like a reasonably big city, and they had a pretty big hardware/tradesmans shop there (afraid I can't give directions, but it was a few streets west of the main street in town). Undoubtedly they would have helicoils. So if you can make it there and ask around you will find something to fix it.
Most likely you will also find a fellow biker who will invite you home and insist you stay and eat while he fixes your bike. That tends to happen in Russia...
Vladivostok - Denmark 2008... Finished.
Denmark - South Africa 2010-2011... Finished.