Hello Jamal

There are no average parameters for "motorcycles". From dirtbikes to scooters, to superbikes is a world of different values.

Honda does not build the GY200. This is a Chinese copy of the XR.

As with many "copy" motorcycles, info will be very limited.

You can find some info here:

https://www.bikez.com/motorcycles/chang-jiang_gy_200_2007.php

If you want the spring stiffness, you can measure it yourself very easily by taking the spring apart, compress it with a known force and measure the change in height (F=kx).

Is your deeper question about setting the sag height? Your shock may or may not be adjustable to accommodate a proper race sag. If not, then you'll need switch out the spring or purchase a different shock.

Here are decent instructions for setting the sag:

https://www.procircuit.com/content/Setting%20the%20Sag.pdf

thanks Dear Ceser and Thom for answer