When you buy a bike new you get a little coded strip with the code needed to cut new keys if you lose both. Of course, odds are you lost the little coded strip way before you lost both keys. In that case, you can call the manufacturer (or have the dealer call the manufacturer) and as long as you can prove you own the bike, all they need is the VIN to cut you new keys. The only thing that sucks about this is it takes a week or two to actually get the new keys you ordered.

If the locksmith says they can cut a new key if you just bring them the bike, I would go that route unless you don't need the bike for a week or two.