[mangoandmimi]

As alpacassei said it may well be that he is territorial. Although it doesn't seem as common in Syrians. Have you seen what he is like outside the cage, often territorial hams once in a playpen are absolutely fine. That might help determine what the problem is. If a food bowl is a problem it might help to just scatter feed it to be honest then he might not lunge.
But I would also be interested to know what the cage and setup is like - it could also be that he feels unsettled or afraid. Are you doing frequent cleanouts? Anything much more than a full clean every month with spot cleaning here and there would likely unsettle him if his nest or hoard disappears frequently.