how do you know the proper position to set c-clip

[Captain Rainmaker]

The clip is for adjusting part throttle. If it runs fine at part throttle, leave it alone.

 

[Wrench]

The needle clip will adjust more than part throttle. Ya want to know how it performs at full throttle.
Will a 4 stroke bog down at full throttle? Or will a 2 stroke start 4 stroking at full throttle? Assuming ya got it jetted correctly.

 

[Vikingimike01]

What how do I know??? Just set it to the richest (bottom) and go up from there. Better than having it lean