is this bicycle possible to put a motor

They sell some chopper bicycle motor mounts plates on EBay that could be adapted to your DBack chopper.

I don't think the adapter plates will work with that piece of steel that comes out of the seat post, but I wouldn't cut that out just to fit a motor plate in there. Its nice to have that extra bracing. I would work on custom mounts, the front could come up from right behind the front down tube next to the pedal crank, and the rear could mount to the seat post above the bracing. Good luck! An engine will definitely look good in that frame.