I have made diy transmitter and recevier and center position is 1500 and throttle is also 1500. I am working on diy quadcopter project.
2 motors are working fine with low position and running at same speed but having issue with 3rd and 4th motor.
3rd motor starts running at throttle position is at center position and 4th starts running at above center position.
Two esc are readytosky 30a simonk esc and 2 esc are normal 30a simonk (without coompany name color: red and yellow).
Before this, one of my esc brust and that burst esc and motor are hotter than other.
I have checked transmitter & RECEIVER. THERE IS NO PROBLEM WITH TRANSMITTER AND RECEIVER.
So,What is the problem?
Please help me...
Thanks..

Two esc are readytosky 30a simonk esc and 2 esc are normal 30a simonk (without coompany name color: red and yellow

That might be the problem !

Caliberate throttle separately for each Esc/motor first, so that each Esc understands the same throttle position

I recommend not to use two different brand esc's together as they both will have different respone time . I think that's the issue.

I have replaced one esc with readytosky esc but esc are getting hot and motor is not running.
What is the problem now?

Did you try the suggestion in reply #2?