Brushless motor shutters
 

<div style="margin: 0in 0in 10pt">I have a motor that sometimes just shutters the prop back and forth and will not spin. This only seems to happen when starting the motor from a dead stop it does not happen in flight. Even if I try to go to full power the prop stills shutters, after a few tries it seems to finally spin up and work correctly. Any thoughts on what might be going on? I thought this could be a timing issue but have not tried to change that yet. Right now the timing is on low.</div>

RE: Brushless motor shutters
 

It's not supposed to happen, but sometimes just playing with the wire combinations will cure this problem (experience, no theory). After that check for poor solder connections at the windings. finally timing.
Walt

RE: Brushless motor shutters
 

If its a Castle you might try slowing the ramp-up start current. Also, if it works OK in flight, just to live with the problem try quickly reducing the throttle to zero and up again a few times to get it spinning.

RE: Brushless motor shutters
 

The speed control and it's settings are a possible culprit.
You can try reversing two leads, but I doubt that is the solution.

RE: Brushless motor shutters
 

The motor is controlled by the Esc, so its setting determine how it works. Did you do the throttle endpoints calibration? If your Esc has it, set it for the cell count your using. Check the start mode, it should be set to Normal. If it stills stuuters a t start up, try medium timing. Most Esc are defaulted to low timing, some motors need higher settings. On a few Esc's, PWM is adjustable, I'd use 8PWM, that normal for about 90% of all outrunners. FWIWflytreetimes

RE: Brushless motor shutters
 

Or its a poor solder connection. And repeated operation will eventually damage the motor and or esc.

A poor connection causes resistance, resistance in turn causes heat. Heat causes material (metal) to swell. When it swells it makes a better connection, and it starts to work.
But that bit of resistance is acting like a dead short, and not making the motor nor the esc happy. And when they are not happy the magic smoke can leak out.

Go back and look real close at your solder joints at the motor and esc. If you see a dull looking solder joint, you have a cold solder joint and it's making a poor connection.

RE: Brushless motor shutters
 

I agree.   it is either a bad solder joint or a bad ESC.  Resolder, test and then either fly or replace the ESC.

RE: Brushless motor shutters
 

Added resistance acts like an open, not a "short".
Due to the wire size, and the usual ~ 40 watt soldering irons, it's quite easy to get a cold solder joint at the motor leads to speed control lead pins.
I partially prefill the pin cups with solder, and put some fresh solder on the leads, then do the actual soldering.
Using rosin paste thinned to a liquid with "Golden Grain" also helps.