I heard it’s not even the core temperature but actually pretty low. When I remember correctly it’s around 34C. That’s a Temperature even we in Europe will experience in summer regularly.
AFAIK the second best thing to do when it’s really hot and you’re on a motorcycle is: Make your underwear wet with water and put on your outer layer as insulation. The water will evaporate through your clothes and prevent the body from creating too much sweat which will cause dehydration. Repeat when you get dry.
The best thing ist to not ride a motorcycle for long periods of time under these conditions. I would maybe commute for up to an hour but never ever go touring when the temperatures reach 40C. It’s just too damn hot and you need more water then petrol