I applaud your honesty! You could probably put a price on the bike's value. Your integrity, however, is priceless.
100% agreed !! I'm sure if there were any complications, you'd be well supplied with character references. I would also submit that your efforts at salvaging are also worth something, unless the PO is in Iraq, or something equally unavoidable prevents him caring for his property, and I don't necessarily think jail qualifies, if he does want it back, you should be compensated. Its probably more likely that the last reg owner sold it to someone who didn't know/want to take care of it, or register it, rode it till it died or sold it before it did, and the 3rd or 4th guy just decided to cut his losses. Could be that the 3rd or 4th guy is unavoidably detained, but without a paper trail, who knows? Keep chasin it, makes a great story!
As to going over the state lines, registering and coming back, you can't do that here (in the USA) legally either. CA and OR give you like 30 or 60 days after becoming a resident to change it and start adding fees if you don't. OR is fairly lax about it, or maybe there's just less cops here. CA is big on giving tickets if a local cop sees the same out of state plate consistantly. WA will too, so many people buy cars in OR to avoid sales tax that WA assesses a sales tax to every car that come into the state and gets registered. Here on the border, lots of WA folks run OR plates and vice versa, but you can get a ticket for it. All states (afaik) have similar laws. Definitely a lot of BS involved, so I may have taken an occasional paperwork shortcut back in my youth...

heh..gettin hard to remember that stuff now dontcha know...