Have a rebuilt E81 motor in a Trike, replaced head gaskets but stil over heating, Rear mounted radiator. Has thermo fan fitted. Can any one please help?

Edited December 6, 201312 yr by Rich79

Is very hard to remove all air in rear rad setup try a rad cap fitting off upper heater hose so you can fill engine before startup you will have a air pocket traped between rad and lower rad hose conection and will most likely be very hard to fill. My rear rad cooling sestem hold 20 L of coolant the more coolant the more cooling medium at any rate make shure no air in engine or could damage it

can we get some pics?