I had a 30cc homelite on my sons Balsa USA WWI DVIII.Thats the high wing monoplane.
84 wingspan.14.25 lbs RTF dry[no gas].
18x8 dynathrust,and an 18x8 top flite.Both of these are not the most effecient prop in the world as people say but it got the job done and without a lot of prop noise.
Anyway,flew around most of the time at 1/2 to 3/4 throttle with no problem.No mods where done to the engine except a pitts muffler.Kept the flywheel and mag on for weight.
I coul hand start it everytime with only 3-4 flips.after i choked it.