RE: KV Rating??
Your 3 cell Lipo is about 10 volts (11.2) so multiple that times the Kv and your motor wants to run at 42,000 RPM. If you prop it for that RPM it will run OK but I don't think that is what you want.
Kv is also a measure of how much torque the motor will generate, high Kv motors make less torque per amp. If you reduce the Kv by half the amount of torque per amp will double.
So your high Kv motor sucks at torque but makes high RPM.
You need a gearbox to turn some of the RPM into torque.