86 xr200 rear shock??

Hi guys

Ive got a xr200 its an 1981 and the rear shock is shot so i had a 86 rear shock for it i just put in today but its not the flashest ether.

I took it out and bleed both the shock and reservoir best I could with new oil and the shock still isnt flashest what have i done wrong??

It does have a valve on the reservoir am I suposta fill that with nitrogen?

Any help appreciated

86 xr200 rear shock??