I can only guess that it is a Hyper.21 or Macstar.28 from the pictures?
If it is one of the above engines then there are roto bits that will fit...
http://www.ebay.com/itm/Hobao-Hyper-...item48715a5a76
The .21 and .28 can both use this roto.
The pulley that you have in your hand in one of the pictures will need to be removed from the starter shaft (just pull it off)...put the starter shaft back into the engine backplate (will take some jiggling to line up the turbo fan/one way bearing)...then install the roto bevel gear and then housing.