RE: Suggestions for L-4 Cub motor
A .56 should be plenty and then some for power, as the .65 flies the 1/5 scale very well. The .56 will stick out a bit from the bottom, but might be worth looking at how well it fits otherwise. I have no problems with any of my inverted 4-strokes, and I have had as many as 5 of them, all Saitos. Just make sure your tank height is correct with the spraybar, and get the needles set correctly, and it will run just fine, the engine doesn't care which way it is pointed.