If someone had told me this was their problem, I never would have believed them;
The piston rings were not round!
I did a compression test at several mileage intervals. Dry to wet numbers were always 30lbs. apart. There was no improvement from 1000, to 6000 miles. All the cylinders were within less than 2lbs. variance each.
I figured I must have screwed up something, as the rings refused to seat in. After running it for a year and 6000 miles, I decided to pull it out, tear it down and start over. I thought either I hadn't gotten the bores clean enough and the cylinder walls glazed over, or, maybe I put the rings in upside down, or, the carb was too rich and glazed the walls, or. . . . ?
Cylinder walls were perfect and looked as good as the day I assembled it. The cross hatch had no signs of anything fishy going on.
Upon closer inspection, I could see uneven wear on the compression rings. Most noticeably on the second ring, as its wider. There were large dark (unpolished) spaces along the rings, where they never contacted the cylinder walls. After looking closely at the thin top rings, I could see they were worn just as uneven. Polished width varied from normal, to almost none.
I gave it a light hone, cleaned it up, put in some top quality rings (Seal Power/Perfect Circle brand), reassembled and tried again. No smoke and no oil usage in 900 miles. I mean not an ounce of oil usage!
Before the "re-rebuild", I was going through a quart every 800~1200 miles. The oil was getting dark, by 2000 miles.
Who knew?
I saved the old rings, so when my friends tell me I'm full of BS, I can show them the proof.