Picked up a used 14' Rzr 800 Blue and white with EPS, about 3000mi on it, ran great when i test drove it, no knocking or ticking. I drove around on the back roads near my house and everything seemed fine(put maybe 10 miles on it) and just before I got back home it started to knock a little bit. Limped it back home and started to look into it.
Thought it was a bad bushing or something in the primary but took it off and motor still knocked. Did some searching on these forums and found that my oil pressure regulator was stuck in the up position(top of plug/dowel was 1" from top of casing). I figured that must been my problem so I cleaned it all up and cleaned up the hole it goes into so it moves decently freely. Tried running again after fixing the oil PRV with a test gauge. Get 10-15psi at idle and sounds good most of the time with no knocking but as soon as I rev it up to 3000-3500 it starts knocking again but has 40+ psi. Its hard to read the gauge and keep it reved it and I dont want to run it knocking like that.
Did a compression test and got 165 and 175psi cold.
Pulled the valve cover off and all valves appear to be moving about the same(was thinking collapsed lifter?), then pulled the rockers(which do have some side to side play when no pressure is applied, is that normal?) and push rods out. Used my pen magnet and I can move the lifter up and down inside the bore easily.

Not super familiar with these Polaris motors as I've rode BRP since the DS650 came out and everything I've had before is always overhead cam. I'm hoping its something I'm just missing and can get fixed in a few days as I am supposed to take the RZR and outlander on a week trip but its not looking very promising. Hoping I did not get screwed buying this but everything I read looks like I'm going to have to pull the motor.

 

You might get better results on one of the razor forums
Good luck