Well the throttle linkage should be isolated,meaning that it should not be a metal rod and metal clevis to the servo arm or engine.
Also,the set screw method is unreliable and needs to be changed to a secure attachment.The vibrations will likely kill the little choke servo,go standard size or do it manual or get an ignition cut off.Manual and Ignition cut, is light and safest.See SmartFly products.
For the throttle rod use a NyRod or at least some plastic clevises at both ends.
This Edge will probably take the weight and power of the 50cc,if you can get a NIMH 1000mh to run ignition and perhaps A123 to run the receiver,it will help take out a bit of burden weight.Use a wood prop.
Good luck with it