It's not that simple in California, what u can do is go to the dmv n fill out a lease sell form, stating u worked on the bike n that its been sittin at ur shop for w/e amount of time its been there, set the estimate price for the work done + storage fees to what this guy owes u, if he claims the bike he would have to pay u that amount or it becomes ur property if he doesn't. Saves u all the trouble, do things legally, GL bro.