hello to all the members once again got back to rc after some time as i was busy with some serious work.today when i was flying my slow stick it crashed as i repaired it once again started flying and once again crashed.
then i started inspecting my stuff and came to know as my motor is giving jerks for some sec while running and then i tried with different set up one again with one of my scrach builds but that happenned once again.so now i am in dilema what is wrong is there any fault with my tx its futaba 6exa and 2 recievers that i have checked  are futaba and turborix and both are doing the same some times.even i have replaced all electrics with the new one.so plz help me to find out the problem.

Hi Sorav

Its probably because during the crash the motor shaft might have become out of shape or the bearings inside is messed up. Sometimes crashes can mess up the alignment too. I assume you crashed nose first? Did you try to rotate the rotor using your fingers?? Does it have any free play?

Hi Sorav ,
If the motor is just  jerking a not rotating  it is most likely that  the is a loose contact in the wire  between the motor and the  ESC  or  one of the  three wires from the motor to the ESC is either cut or has a loose contact. This  affects the commutation in the  Motor .
This  could have happened  due to the crash .
If the commutation in the motor was OK  the shaft has to rotate .
If the  shaft was  bent then there would be a wobble in the prop but not much of a problem in the rotation of the motor , the best way to do this is to remove the prop and try to run the motor without load  as the motor runs the bend will be easily visible .

The other possibility is the Grub screw or cir clip binding the BELL to the shaft  could  have got loose in such case the Shaft with Load  will not  rotate while the bell tries to rotate  thus the  prop will not move

sai

thanks sai sir.but the real problem is that the motor is spinning fine but after some time of running it just gives a simple jerk as if it is not getting any supply i wonder does there can be any problem with the receiver or  the transmitter signals.as the problem is with all the motors that i have and all the motors have met with the severe crashes.and wanted to thanks once again to you specially sai sir as i am still using that 2650mah lipo and now with out any fear.

Hello Sorav,

I think try a new esc to the motor. May be there be a problem with the ESC. 

sorav,
have you set up the max and min throttle on your esc.

http://www.rcindia.org/electric-planes/normal-start-up-procedure-for-electrics/

Please  re set the motor using this set up procedure  and then check if you have problems .

sai