B44 and 2 motors burnt

[msm]

Hello

Running LRP Sphere Comp Speed,4800 Reedy Lipos Orion 5.5 motor 84 Spur and 20 Pinion

First I used a 17t Pinion and 84 Spur Motor was getting hot changed it to a 20 Pinion and was still getting hot about 170F then motor burnt...

Second a Novak motor the SS5800 20P and 84 Spur same thing motor was dead after 8mts

Planning to get a Mamba Max 5700, or try another motor maybe a 7.5 from Reedy or Tekin, but I don't want another dead motor it's $$. Any advice on the gearing?

Pic of the track

Regards