If the bike is legally his, as in when he bought it he spent the sales tax money when he transfered the title registration to his name. If that's the case and lost the title he/the legal owner can file for a duplicate title. Some paperwork, $40 and 2 weeks. If he never changed the title over to avoid taxes(common screw up) he is NOT the legal owner and you'll have to hunt down the guy that sold it to him and do the title sign off, bill of sale etc. Been through this trip in WA before and no the DMV won't give you the legal/registered owners address. In my case I traced the guy, he moved to MT and wasn't concerned with my problem.
Bottom line: if the seller is the legal/registered owner HE can easily get a title. If he isn't or doesn't want to be bothered with it...it's just a cheap parts bike...pay accordingly.