Lorne,


Being a beginning modeler, you should learn some basics.

Using a larger engine will make you plane heavier.
It is not only the engine that weighs more, but also the larger fuel tank and the counter-balancing in the tail (which can be averted if Brian's approach is used...).

Your engine of choice should be the same weight as the intended engine.
More power? No problem. You can always throttle back (unless Curt is right...).

More size and weight; I wouldn't recommend it. It is just adding to your problems.

Models are always overpowered, with their basic engine size even.

Propped ideally, a .40 size trainer, with a .40 engine, would put itself up vertically.
Even with a regular 10x6 prop, it would climb at 45 degrees...
Can you imagine a Cessna 152 doing that?

To learn to fly your model on the wing, as it was designed to fly; not hang it from the prop, just get the recommended size engine.