Been messing with electric helis for the past five years. I have about 4 Belt Cps and about 5 King2s , several Coronas, many Honeybee cp2s/Blade Cps , MX400, Zooms, etc...etc... have close to 30 helis if not more.
The issue with the belt Cp is the ESC. They give you a cheapie 25 AMP esc. You should at least be using a 30 or 35 amp ESC. The King2 going brushless would be a candidate for the 25 amp ESC. At best, you are boarderlinning the ESC.