Don't remove fun, just connect " - " (minus) to frame and it should start or remove connector from rad temp sensor and connect to to frame - fan should start. Also check FUSE - this is should done first, because generally this is main problem :)))or, you can remove the rad fan, and do a direct connection with the battery to check whether the fan and thermo switch is faulty or not.
BTW - I have fitted 20% bigger rad from CBR600F2 pretty bolt-on and never have overheating this season...