2009 Smr450 Overheating

Hi all, looking for some support with my husky, it’s a 2009 SMR450 and it keeps overheating. I can’t figure out why it keeps overheating, I have upgraded the water pump to the RR type to possibly increase the flow of coolant. I replaced the temp sensor on the cylinder head, I have checked all the clutch plates to see if they could be contributing to any overheating but they are in spec. I have replaced the radiators once and just blew a hole in another one today. Any suggestions would be greatly appreciated.
The bike has got the 1.8bar radiator cap on it and the expansion tank was half filled with coolant.

And you have check every thing, to see there is no coolant flow blocking and what water pump is spinning

Yeah, everything checked out fine but seems it’s the head gasket that’s gone. Thanks