Turns out that the piston I had first installed was indeed .5mm too small. I was able to get it to run correctly with the obvious correct sized piston. Now begins the fun part of building something to put this bad boy in.

Hello all. Names bailey. I bought this lifan 200cc 163fml motor awhile back and have since been piecing it together to get it to run so i can build something to put it in. Since owning the motor, I have replaced the piston and rings, replaced the valves, valve seals, valve seats, valve springs and valve keepers. All the gaskets have been changes as well. I collected the electric parts to get it to run and wired it up correctly to do so. Here's the problem. Every time I start it, the first second, huge amounts of smoke start to come out of the exhaust. Oil is somehow finding its way into the combustion chamber and I cannot find out where or why. Have any of you ever had this problem and don't mind pointing me in the right direction? Thank you all.