So i managed to get some mt2205 2300kv and some Emax 12amp ESC off amazon for free (Using a giftcard that i found).

I popped them onto the martian reptile frame set everything up and was ready to go however i have noticed that one motor (Back Left) will not spin up when all the other do. 
I have set min throttle and checked everything it just doesn't want to spin correctly. 

To take off i have to arm the quad and put it in self level punch the throttle and pitch forward at which point it tilts back like its going to flip and boom shoots into the air and from then on its fine however this is a very dangerous procedure as i found out the other day.

Anyone know what it could be?

Very wierd problem... Is it BLHeli? Have you checked PPM Min and Max?

Which emax ESC is that? EMAX nano or old-school emax "simon" (but really BLHeli) ESC?

(09-May-2016, 04:26 PM)Oscar Wrote: Very wierd problem... Is it BLHeli? Have you checked PPM Min and Max?

(09-May-2016, 07:41 PM)Konrad Stepanajtys Wrote: Which emax ESC is that? EMAX nano or old-school emax "simon" (but really BLHeli) ESC?

Everything seemed fine when testing it but took it for the maiden flight and ever since i got to the park it was doing it. 

Its the old school Simonk hopefully gettin little bee's soon but they came with the motors so just thought id give them a go

Than those ESCs are very crappy on low end of throttle. I assume You tried calibrating. You still can set low throttle higher on FC (i had to set 1200 on 3s pack, lower on 4s).
You can connect and flash new blheli on them to be able to check its settings by following this video:

You don't need to solder leads, I found those copper pads were very crappy - pushing a set of pins is enough to reflash.

(09-May-2016, 08:46 PM)lolFPV Wrote: Everything seemed fine when testing it but took it for the maiden flight and ever since i got to the park it was doing it. 

Its the old school Simonk hopefully gettin little bee's soon but they came with the motors so just thought id give them a go

Less-than-perfect motor-to-esc solder connection maybe?  (Just mentioning, cause I had something sort of similar on a build recently - seemed to punch in at higher throttle. Turns out that resoldering the leads on that motor fixed my problem.)

(09-May-2016, 08:57 PM)Konrad Stepanajtys Wrote: Than those ESCs are very crappy on low end of throttle. I assume You tried calibrating. You still can set low throttle higher on FC (i had to set 1200 on 3s pack, lower on 4s).
You can connect and flash new blheli on them to be able to check its settings by following this video:

You don't need to solder leads, I found those copper pads were very crappy - pushing a set of pins is enough to reflash.

Thanks for sharing that video i might give it a go later on this week.

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(09-May-2016, 09:01 PM)sloscotty Wrote: Less-than-perfect motor-to-esc solder connection maybe?  (Just mentioning, cause I had something sort of similar on a build recently - seemed to punch in at higher throttle. Turns out that resoldering the leads on that motor fixed my problem.)

Ill take a look at the connection tonight but i'm pretty sure they were near perfect. Hopefully it is something as simple as this though. Thanks for the help

So i have taken a look at the soldering between the motor and ESC and everything seems fine.

Im not sure if its the ESC or the Motor but the ting just doesn't want to start up when the others do.

I now have min throttle set to 1300 so on the rare occasion it does take off and not flip over it jumps into the air rather unpredictably.

Anyone got any advice on what to do ???

This may be a stupid suggestion - I use them now with a bottom mounted battery, so it has to balance itself (does it better with airmode BTW) before takeoff, using low throttle. Maybe try fixing something similar to a pack to the bottom so it doesn't lay completely flat and test?

EDIT - that may actually work even better with horizon/angle mode

I just noticed that these ESCs have BECs. Are you powering through only one BEC, and if so, is that the motor that is giving you fits? (Don't know why it would make a difference, but you might try powering through a different one to see what happens.)

(23-May-2016, 11:29 AM)sloscotty Wrote: I just noticed that these ESCs have BECs.  Are you powering through only one BEC, and if so, is that the motor that is giving you fits?  (Don't know why it would make a difference, but you might try powering through a different one to see what happens.)

From what i know it is being powered through all 4 BECs.

I have got spare motors and ESCs at home so tonight after work im going to swap the ESC out and hope that fixes the issue.

(23-May-2016, 04:46 PM)lolFPV Wrote: From what i know it is being powered through all 4 BECs.

I have got spare motors and ESCs at home so tonight after work im going to swap the ESC out and hope that fixes the issue.

Than this situation is not ideal - You should power only trough one ESC. Best is to power from separate BEC.

I know that You will swap them anyway, but are You using 3s or 4s with them?

(23-May-2016, 06:54 PM)Konrad Stepanajtys Wrote: Than this situation is not ideal - You should power only trough one ESC. Best is to power from separate BEC.

I know that You will swap them anyway, but are You using 3s or 4s with them?

The only reason im not powering through a separate BEC is because these have them built in. 

When i finally get round to upgrading to little bees then i will consider the BEC.

Swapping the ESC has fixed the issue must have been a dud as it was brand new

(24-May-2016, 12:40 PM)lolFPV Wrote: The only reason im not powering through a separate BEC is because these have them built in. 

When i finally get round to upgrading to little bees then i will consider the BEC.

Swapping the ESC has fixed the issue must have been a dud as it was brand new

That happens I was asking 3s or 4s because those ESCs work on 4s but better not use built in bec as it overheats VERY quickly and weird things start to happen.