Hello, I am running a 3dr y6 frame with an APM 2.5. I just ran auto tune and it flies pretty good except for Yaw. I can go full stick right and it only yaws slowly. I can do the same to the left and it turns a little faster but not anywhere near what my other hexacopter does. PID settings are stock. I would think that stock settings would function better. Do you think somethings wrong or do i need to tune some.
Check your radio settings. Any dual rate? hook the APM up to your computer and see what it’s registering as far as signal goes from the receiver.
Double check that you have indeed put the propellers on the correct way. Yes they are providing you all thrust. But they could be spinning the incorrect way and that would totally screw your Yaw. did you accidentally mix the arms up when you were putting the motors on?
Yaw should be fairly fast. 1.5 sec~ ish on mine to do a 360.
If the motors are on wrong or the wrong direction or props on wrong it would not fly. It flies fine. Pitch roll and throttle all work fine. It just does not yaw very fast. It does ok to the left but when i yaw right it needs full stick to get it going and then once i let off it doesnt stay, it will rotate slightly back to the left.
Its like the lower motors are not providing enough thrust to rotate.
I bumped the Rate P from .150 to .250 and its doing better. I will keep messing with the gains tomorrow. It got dark on me so I had to go in. 
Ok, you were right. two motors on one arm were swapped. So when i tried to yaw the motors were fighting the other 2. I changed the leads and now it flies much better. Still need to fine tune the yaw but I am happy to have that sorted out. Thanks
Glad it’s sorted out.