i need some advice. this is the probulem . 250 frame 12 amp blheli with bec. four e max 2300 kv motors. kk2 board.was using a cc3d board but switched to see if that was the trouble. no luck there. all motors spinning in right direction. now when the props are off all four motors spin up.at the same time.when i put the props on maybe one will spin the other three just shutter no matter how much throttle i give it. i have trying to solve this proublem for about a month. i google and google but no results. so if any one has any ideas i would very happy to here thanks in advance.