As for the CA Extra, I think it will take a 50cc gasser. Go to 3Dbatix.com to see my friend Zak 3D his with a ZDZ 50.
PS: While your there, check out the vids of my friend Meyrick's H9 Edge. (which is now mine)
Check out all the pics too. You can find both the Edge and the CA Extra in there.
Some great vids and pictures on there! Great site!
3D-kid330