I have a 20 amp esc and a 7.4 v 2 cell 1800 mah 25c lipo.
now I am making a trainer with coro and my calculation shows the plane is 456 gms with battery,servos,reciever and esc. I also added the weight of a motor ( Avionic C2826 brushless motor ) which is 50 gms. Avionic C2826 gives 650 gms of thrust with an 8x4E prop combination which is correct configuration for my plane.Is 650 gm of thrust enough for it to fly quite fast ? The link for motor is given: http://www.rcbazaar.com/product.aspx?productid=1910

More than enough , but why such a setup on a trainer ? Why dont you down size a bit on the motor and prop , aim for more flight time .