Hi everyone, I am new to the sport and new to this forum.
I started flying a few weeks ago with a Lan Yu trainer powered by a .40 engine.
I would like to know if too big of a prop size could cause the engine to cut out at lower rpm?
I am currently using a 10-8 prop. Is that too big for this engine?
It is an old engine (about 20 years old) but it seems to work just fine until I ease off on the throttle.
My instructor has set the engine's fuel mix but it still dies on me every other flight leaving me with a hair raising powerless landing.

Thanks,
Ray