@Go***
it was a pushbike so no paperwork. Motorbike might be more complicated for sure, but if you just wanted to do a border bounce you could park it on the Thai side and walk over to Cambodia (the customs posts are right beside each other). If you wanted to go on to Koh Kong for a night or two you could leave the bike in Thailand and get a moto taxi to Koh Kong which is around 10km from the border.