250-500cc Low compression...

So I had a full rebuild about 16hrs ago and new top end about 6...the bike runs great and always starts up first kick but is way low on compression. I can turn the kicker over by hand kind of easy but you can still feel some compression. ...it had good compression after new top end...I think it was like 190? But anyway what would cause it to go down so much in a short time besides air filter cause always has clean and oiled one plus it looks to be sealed good. I have a steel sleeve in it( how I bought it). I checked it and didn't seem to be out of round at all. If it's not perfectly smooth will it cause it to drop? I'm gonna pull it apart and check everything. Another thing is that my squish is like 2mm. Will that cAuse it to be low also? 91 wxe 250. Thanks

Pulled the head off and looks like my piston to bore clearance is kinda large? What is the reccomended clearance? Plus my ring Gap looks big but i measured that before installation and looked fine.

EDIT: My piston ring has had its outer coating worn off. My bore is really smooth, so I guess gonna have to re ring in. I don't see anywhere that dirt is getting through the air filter but I see that the only cause. My piston doesn't have lots of lines going up and down like you would think if it was sucking in dirt. Any other things that would cause this?

Your bore might be "really smooth" to the eye, but it may not have been finished to the proper specs for your rings. Were they OEM rings or aftermarket?

They are wossner...I'm wandering if the rings are made for nikasil and I have a steel bore? It wears off the nice shiny coated edge of the ring and that's it..