OK, Does the motor turnover by hand/socket ?.
I had a YD100 that was a b*tch to get it to turnover. I had to slam all my weight down on the seat when I popped the clutch.
OK, One last try at this... Take the plug out and see if the motor turns over freely when you try to peddle start it.
We'll go from there to figure out the problem.... You got something weird going on.