Took all the preload out of my rear spring, about 3/8 inch, put about 20 miles on it in the Mountains.
DANG what a differance, no more hard sideways movement when a rear wheel hits a hole or rock.
Front and rear suspension seems much more balanced now, go faster in the rough stuff without back pain.
Another Guy wrote in a week ago about doing this, and I got off my lazy butt and changed mine.
Used a punch and a hammer to move the two rings, easier than a wrench.

If you weigh more than 200lbs, ride double or carry a lot of weigh on rear rack, this might not be for you.
But it made me not care about a IRS machine.
Love that Prairie.

 

I notice this on lots of different ATV's except for the Rincon because it is plush. Get someone near your weight to ride your ATV while you follow. Chances are if you have not adjusted your rear shock, you will notice the rear suspension is not working very much. My partner noticed when I ran over a 2" stick at slow cruising the whole rear of the P650 lifted instead of the shock taking it up.