TPW

I'm trying to get a basket case Polaris 400 started. The motor was locked up when I got it and it is now free and turning smoothly and no apparent damaged to piston sleeve, I rebuilt the carb and put fresh gas actually used premixed 50:1 fuel. Has good spark and 70 lbs of compression. Can't get it to do much more than an occasional bark from the engine. Any "next steps you could recommend would be appreciated.