Well small ... go and back took me about 2 hours. At Song Khwae I took route 1279 in direction of the signs "Thai Lao Market Place". And of course that was the last sign in English.
The road is passing 3 small villages and about 10km of the road is in bad condition with a lot of put-holes. And currently (26 August 2016) at a few places they are working on the road.
A few km before the border there is a border police check point where non-locals are being checked. I had to register myself and we had a chat about changing my motorbike for one of theirs. But changing my Z250 for a Honda Dream was not a good deal.
Once you get at the Thai side of the border the road turns into a dirt road. It seems that the border was once setup to become international with signs in English. But at the moment it is only for locals. It is called "Ban Mai Chai Daen".
Every Sunday there is a Thai market where Thai sell all plastic and things to the Lao people. It was busy with many school kids, soldiers and other people. I did learn that there was a "tree planting" party. So nobody was bothered that I did walk into no-mans land to Laos. The real border is about 900m from the gate. But due to the mud (it had been raining) I skipped that and did ride back to Song Khwae to take route 1148 to Chiang Rai.
For the rest of the motorbike trip see On the motorbike from Nan to Chiang Rai