P35, Take two 1-1/2 x 2 inch x .083" steel plates and weld one edge of each to the underside of the motor mount where it meets the large holes in the frame. Then bend with or without heat the plate so that it conforms to the OD of the frame tube. Clamp the free end down and tack weld to the frame tube so it won't spring back. Finish welding all the edges of the plate to the tube. On the top side of the tubes fill in all the holes with rosette welds and grind smooth. Cut a new motor mounting plate from sheet steel and place over top of the trashed one that's now on there. Do some edge welds to hold everything in place. Unless someone turns your bike upside down they will never see the repairs. Ogy