replaced radiator on my Ducati 1098 now running hot cant figure it out

My Ducati 1098 had a hole in the old radiator, i got one on ebay for a good price so to save a thousand dollars i fitted it myself i put coolant in it and took it for a test ride, it was ok then started running hot got to 102deg so stopped it and noticed the refill bottle was full then drained into motor now its full and i took off radiator cap and it to was ok, but the bike is still running hot when it idles ???