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Some motors late starting

Firstly, yes a newbie doing my first build.

Hexcopter (X)
KK2.1.5 FC
SimonK 30A ESC
920 KV motors
Spektrum DX6i
F550 frame

So everything is hooked up and just getting ready to mount my props (which are now balanced).
But when I go from throttle 0 to throttle X. Six of the motors (m3-m6) all start together. M2 was sputtering for awhile so after reading this forum , I swapped the ESCs between M3 and M2. That seemed to work. That was yesterday.

So today, I go back to continue my adventure, ensuring the motors are all turning the right way, and I discover M1 and M2 are stuttering. But if I crank the throttle to about 20%, M1 will start, and then at about 25% M2 will start and all the motors are running.

So, this is normal, qwirky, or magic?

I know bad connections are discussed and I check my bullet connectors between ESC and motor repeatedly. Unplug, wipe clean, insert, turn, tight fit. Try again.

Thanks in advance.

Foam Addict

Squirrel member
I second the Welcome!

Calibrating the ESCs is simple, but not something to be trifled with. First remove all your props, next, power up your transmitter with the throttle in the full up position. After that, connect the Battery to your Hex while holding down the outer 2 buttons on the KK 2 board. Wait for the first set of beeps (I can't remember what the Simonk Throttle set tones are) and then throttle all the way down. Finally, release the buttons on the KK 2 and reinstall your props. That should calibrate all 6 ESCs simultaneously.


Crashing Ace
let me stress TAKE OFF THE PROPS i can tell you how often ive calibrated and the thing goes full throttle but i always take off the props so i wasn't harmed.
Okay, I'm really not enjoying the frustration of troubleshooting.

So, I follow Foam Addicts instructions and the KK plays a little song after I put throttle to zero, but I didn't get the see the display message.
And after that the motors are all starting and stopping together. They are playing together nice.

So then I realize that my motors are hooked 2-7,1....so of course I have to change the connections on the KK. Done.

Try the motors again and M1 is stuttering and won't go....oh, I must have to recalibrate again.

I do the calibration and at the end all I get is two beeps, no music. Checking the display while calibrating, it says "Throttle passthrough".

I attempt a few re-calibrations and all of them are the same (two beeps, no music). And I triple checked the connections.

Is it time for a factory reset on the KK?

P.S. By the way, during the calibration process, there is no spinning of the motors at all. So not sure why the concern with props. Regardless, they were not on yet.

Foam Addict

Squirrel member
I didn't push the buttons all the way down initially. When I did push them down a second later, the tri launched into my leg and arm. Thankfully I was working in my sub freezing garage, so I had thick jeans and a leather jacket on, otherwise I would have had serious cuts on my arm and leg.
The stuttering sounds like a motor to esc connection got damaged or came unplugged, I'd check the m1 solder connections.


Church Meal Expert
No they should Not spin during calibration.
You plug in the battery with the throttle at full and it will play a little tune (different from normal power up tune).
The tune which is played is particular to each brand and model of ESC.
The motors do not spin at this point.
You drop the throttle to zero and it will play another different tune to indicate that calibration was successful.
Moving the throttle at this point (after successful calibration) will spin the motors.

You need to ensure that your throttle (and other controls) endpoints and midpoint are set correctly BEFORE you attempt to calibrate the ESCs. Also make sure that your stick movements are in the correct directions - throttle is often reverse depending on mfg.
If your throttle is reversed the calibration process will not work.

Best regards,