Motor Overheating in FOC

Hi Guys,

I have a custom built 10 pole, 860kV, 48v, sensor-less brushless DC motor (medium inrunner), that i am trying to spin at 30,000 RPM for a project i am doing, 

I am using a Dual FSESC6.6 6.7, running in FOC mode. I have run the FOC setup wizard selecting the direct drive option and it successfully detects the parameters. After a bunch of tweaking i was able to get the motor to spin at a constant rpm (around 29,000 rpm, 147000 ERPM).

I was only able to do this using duty cycle control and when i attempt to use ERPM control the motor seems to loose position of the stator at higher rpms and just sorta revs upto around 100,000 ERPM for a second and stops, it does this repeatedly.

However, i noticed that on duty cycle control, the motor starts to heat up insanely quick, reaching around 70degs after a minute of runtime at around 25-29k RPM. Is there any setting on VESC i can change to reduce this/ am i doing anything wrong ? I am quite new to VESC. 

Below i have attached the settings i have used, also worth noting that this is not for an eskate/efoil, i just want to get the motor to run cooler.

Thanks