[QC102]

My 250 ZMR (off ebayclone?) wants to go backwards on take off.
Eachine 2204 2300KV - 12A Emax ESX - CC3D.

Having a break from the tribulation of setting up a Revolution with NEO  M8N GPS - due to Aussie's unusual bout of heavy  rain and strong winds making life difficult for poor little quads to fly.... I set about putting together a 250 frame.
Used a 250 template and it gave me problems and I did a new start and  went through the Vehicle setup and   then kept my own settings. Using the stock  PIDs it seems to fly OK - in hover and out of its own downdraft its fairly stable  but wanders about a bit..on  lift of it always moved backwards - I correct and sent it forward... finger off stick...it comes backwards from where it is it at that time.
The motors are fairly quiet  running - no squealing oscillation sounds or wobbles
I have  gone through the set up  three times and each  has this same result.  This is  my first 250 type build and I have not had this happens with my 450 and 500 size frames.  Is it "normal" for the smaller 250 size or  is there a cure I have not found?

[TheOtherCliff]

You should take off immediately after arming and starting the motors.  If you sit there with motors spinning slowly, they will "wind up".

Race mount motors (tilted forward) cause issues like this.  Consider sitting the front end on a piece of wood before takeoff to make the props level.  Hover position is where the props are level.

Never change your transmitter trims from where they were when you did the transmitter wizard.  Use Attitude -> Settings -> RotateVirtual to make it hover level in Attitude mode.
  if it is drifting forward you subtract from pitch
  if it is drifting left you subtract from roll
  etc

[chromvis]

OC102. From what you wrote it sounds like board level problem. Did you calibrate accelerometers and board level?