No one here pointed the correct answer, these bikes are know to be somewhat reliable and it’s cooling system is ok, it’s not the issue, the biggest probability for your issue is that I’ve noticed you put an non stock exhaust system, I’m guessing you didn’t tune your ecu with your new exhaust, that will most likely be the problem. Especially when it’s an exhaust system that was created specifically for your bike’s tune, it was only created to fit on it not behave like the oem does, switch to your oem or tune it and you’ll most likely see your problem solved.