Most 2 meter planes do not have enough wing area to fly properly with a gas engine. Even light engines like a ZDZ40/50 or a DA50 are still way heavier (with ignition and battery) than a 140DZ. Thats why CA plans to make a 2.2M gas AA plane. Chip Hyde came to the same conlusion with his Vision....its is also a 2.2M plane.

It's all about wing loading. The lighter it is the better the plane flies. A 10lb pattern plane will ALWAYS fly better than an 11lb plane. If you take a light plane like a ZN Partner and hang a gas engine on it, it will weight 11.5lb and fly like crap. Even it you get it below 11lb you will have all the servo's, batts and the kitchen sink in the tail to balance it and it will still fly like crap due to de-centralized mass.

To fly properly gas planes need a shorter nose moment (for balance with all flight gear on the CG) and enough wing area to get the wing loading down.

FYI, all current 25-40cc gas engines weigh the same as 50cc gas engines when fully fitted with ignition.