flywheel wont sit on top dead center

[clueless]

Thanks, D, but during this time that i could feel this, the plug was out, the rocker arms backed off and the drive belt was removed. since posting this, I took it down to the block, removing the head and cylinder. as I held the piston between my fingers to keep it off the block turning the flywheel had the same feeling. it felt like it was a cam on something. if you let go at the middle of one of the tight spots it would jump forward or back. could not find a reason for it. decided to put it all together and fire her up. she runs and idles smooth! dont know what to make of this!! run til she breaks I guess and then I will know!!