Almost all states have a process for titling an abandoned vehicle. In VA, you have to pay $8 to DMV to have them run a vehicle title history report. The last person to have the title will be on there with their last know address. You then have to pay the US Post office about $6 to send a certified, signature receipt, letter to the person listed on the report. In the letter you have to include the VIN, your address (or address where the bike is located) and state your intent to title the vehicle. If you get no response within 30 days of the signature receipt or if the letter is returned as undeliverable, you take a copy of the letter you sent, the signature receipt card, the title history report, and $10 to DMV and get a title in your name.
The risk: old owner is still there and wants their bike back. They don't have to give you a dime so don't put any $$ into the bike until you have the title in hand.
Good luck.