I had problems in the master bath with the toilet emptying out completely. I replaced it with a high end Kohler 1.6 lpf which siphons out well. However, now in the other bathroom I am having the same problem. The water swirls in the basin, but doesn't completely empty out, leaving toilet paper behind. I replaced the entire toilet and components with a new one. I replaced the wax rings. I even pull the toilet off and jetted water into the drain and even used a snake. It doesn't seemed to be blocked. What else can I check? I read something about a vent. Could that be impeding the siphoning action of the basin?
Thanks for your reply.

If you had a blocked vent you would hear a gurgle in the bathroom traps when you flushed the toilet od drained the tub. I have one that most repair plumbers miss.. Look down at the bottom of the bowl. If there is a small hole, then that is a jet that starts the syphon action. If it's clogged the water will just swirl around and slowly go down leaving solids behind. Take your finger,(UGH! ) and run it around the inside of the opening. Over the years minerals build up and cut down on the syphon (flush) action. If it is rough or you feel build up, take a table knife and put a bend in it to get around the curve in the bowl and chip and scrap it clear. Next take a coathanger and clear out the holes around the rim. They start the swirling action. And last, check the water level in the tank. It should be 1/2" below the top of the over flow tube. And speaking of the overflow tube, Make sure the small 1/8" tube from the ballcock to the white overflow tube is connected so it discharges in it and that it's flowing when the ballcock fills. This is what raises the water level in the bowl. For a good solid flush they allhave to work together. This is what could have been wrong with the toilet that you replaced.Hope this helps . Tom

Good answer, I like to use a small hand held mirror to visually inspect the under the rim of the blowl