I have the same situation with my build. Its specifications are:
1. SK Lightning 480 quadcopter frame kit
2. Set of 4 Multistar Elite 2216 920 KV motors, 2 CW and 2CCW
3. Open Pilot Revo 32 bit F4 based flight controller with integrated 433 mHz Oplink
4. 4X Afro Slim 20A ESC with SimonK firmware
5. Orange R1020 V2 2.4 gHz DMS2/DMSX compatible receiver
6. Ground Control Station software downloaded from Librepilot.org running on an old Sony laptop
7. USB cable with micro b connector
8. Futaba 9C transmitter with Orange DMSX/DMS2 converter module.
9. 4000 mA 3C Nanotech lipo
For testing and setup, I've tethered my quad to a large piece of plywood to prevent it from lifting off more than a couple of inches.
When the throttle is "cracked" the motors start to spin up like a "soft start" sequence, but, after a few seconds, go to high speed
It's set up using the standard Wizard, with default settings, except for moderate exponential on the throttle curve (added in an attempt to control the behavior I'm encountering).
The alwaysstabilizewhenarmed setting is False, and I use channel 5 on my transmitter for arming.
During setup, with no props, the motors seem to spin up smoothly and linearly, but it's hard to tell when there's no load on them.
When I install some old 6X4 props leftover from my 1/2A glow days, it starts up slowly, but rapidly spins the motors up. They can't generate enough thrust for liftoff, but do jiggle the airframe around a bit.
With putting on the 10X4.7 props, all hell breaks loose, with the soft start followed by high throttle and lots of bouncing around at the limits of the tethers. The airframe seems to respond somewhat to pitch, roll, and yaw inputs, but it's limited by the tethers.
My next plan for testing is to take the Revo out of the equation. I'll drive each motor separately directly from the throttle channel (3) on the transmitter/receiver and use a tach to see if they spin up more or less consistent with the throttle stick.
I have a Hobby King KK2.1.5 board that I can swap for the Revo for further diagnosis.
Any other suggestions?
Thanks