Help, plane wants to roll when looping

If you already checked the elevator halves it almost certainly is the planes lateral balance. You said you checked the wing balance with it off the plane but you really need to check the lateral balance of the plane with the wing on. Ihave a kyosho cap that off the plane the wing balances perfect but for some reason had to add a ton of weight to the left wing tip for the plane to balance laterally. I found that quite odd but it does fly straight!
Happy flying
Tim