Ralpboy,
I don't think it will work but you can certainly try. As of January 01, 2006 a new motorbike passport is required to leave the country. I have know several people including myself that have crossed into Laos before this law. Digby's post shows the tightening of the borders as to riding around as he was rejected to enter Laos. He speaks fluent VN and if anyone could get over, it was him and his riding companion. I tried to cross into Cambodia with my bike at all 3 points and was refused. This was before the new law and the boys at the Chau Doc border are not so friendly. The border below Chau Doc was a bit more loose but also think bribes won't get you across.
Best to try Moc Bai but it's a long shot to sell that bike in PP. If you do, great luck has been with you. There are many reports here about Moc Bai and my 3 hours there trying to get over were a bust, I even had the paper trail of 6 months of crossing into Thailand/Cambodia/Laos and back into VN with me but no was the sad reply.
Let us know!!
It's sad, all we want to do is ride.
Ride Safe