I am just repeating this question from the beginners section, probably not getting an answer there.

I have a 55ax on the GP Reactor 46 but the engine does not seem to have compression randomly, mostly when it gets hot (at running temperature, set half a turn back from peak rpm with now cowl) and cuts at some point in flying. Now, why the engine doesnt have compression is another issue and I will fix it later by replacing the piston-liner set (engine hasnt been opened, most likely it wasnt run-in properly). For the time being I want to continue running the airplane with a 75ax. That specific engine is an older engine which did give me problems on another airplane but those could be tank height issues. I plan to achieve 2 targets b y using the 75ax- find out whether the 75 is reliable and continue flyng this airplane with a bit more power and throttle management in 3D

My question is - is the engine too big for the Reactor or should I go ahead and make the swap? or should I order and install a 65ax on it? I couldnt find reviews of the 65ax anywhere

Ameyam