RE: complete 2 ring Ryobi kit $69.99
On a different side, I have Echo/Kioritz engines that weigh just over 2.5 lbs. including the engine mount that swing a 16 x 8 prop at over 9000 rpms. I have one on a GSP Katana 140 and it flies super! The engine cost me 10 bucks used, and performs great. I don't fly 3D myself, but I'm sure if I went to a lower pitch prop this combo would do it. As it is the vertical is basically unlimited.
The Ryobi does have a poor power to weight ratio, but it has it's applications.
AV8TOR