Hate to resurrect an old thread but my same esc motor combo has the exact same issue and I'm only running 2s.
I can't even finish a 5 minute race with this motor/esc combo and thats geared low at 18t pinion.
I'm gonna try a fan or maybe external bec but this combo should never even have been sold as a kit imho. This esc cannot handle the 5700 at all.
It will shut down between 130-160 deg no matter what motor you run.
Running when the weather is 100 outside it takes 1 minute to reach those temps yet the motor is at a cool 120-122.