We all hope to (and many do) move on to a species-appropriate diet with out any major glitches. If your dog is experiencing any effects that concern you please do look at the Detox post in this Help Section also.
With some dogs, the only issue that owners are concerned about is that their dog seems hungry. There are a couple of reasons for this. When a dog is fed a dry-food based diet, the kibble absorbs water when it hits the stomach, and it swells up to 4 times the size of the dry nugget that went in (hence your dog will have drunk a lot more than he does on a raw moist diet).
With this in mind, transitioning to a diet where no extra water really needs to be taken in and there is no swelling of the raw food in the stomach, the once distended stomach and the "Full" receptors don't get the message. It will take a little time for it all to settle, so don't be alarmed. If you like, do give your dog a pig's ear or another natural chew or treat.
Secondly (but as importantly) after you switch him to a raw food diet, he may be craving the fast food carbohydrates (sugars) that are in a kibble-based diet and your dog's body just needs a short time to adjust.