Hi Reemo,
3 turns from close on the High Speed needle, and then work your way in with minimal turns
Low Speed needle flush with throttle linkage, and then work your way in from there.
Idle screw should be approx 0.5mm opened on the carby slide

the problem with your motor not staying on idle could be a couple of things.

1. your setting could be rich on the bottom end and the motor is loading up,

2. check to see if there is still compression left in the P/L , to be honest 6 tanks is a little to soon to be putting in race tune settings. OS motors are renowned to be a tight motor, and by leaning it out to soon could cause the motor to over heat and cause premature wear to the sleeve.

3. check to see if there is a air leak anywhere, make sure carby is seated properly.

4. repalce the plug.

I have replaced the Crank with the speed crank and yes it makes a big diffrence, i heard the Speed rod is the way to go also.

Hope this helps