baja mini racer won't start after repair

I bought a mini racer, fixed it up, it was losing compression around the spark plug threads, so i ordered a honda g100 head, and new piston rings for good measure.

So I installed the new piston rings and new head, I'm pretty darn sure I put everything back together right. Valves are opening at the correct points in the cycle.

But it won't start now. I cleaned and re assembled the carb. I'm beginning to think I just don't have proper compression.

Is there something I can mess up re installing the piston rings? I clocked the rings, and when I put the gear that moves the valves back in i aligned the two dots. I feel like I'm missing something.

I think I'm gonna take it apart and put it back together again.
i think that pressure is escaping either around an improperly seated valve or around the piston rings

My small engine experience is with chainsaws, usually in good repair, never had to go into the engine before.

I was confident to complete the task, up until the point when I pulled the cord.
resolved: shined a flashlight through the intake valve with the head off, saw it wasn't going all the way down, so i filed off the slightest bit from the tappet and lightly tapped on the head of the valve with a hammer while rotating it until it would seat in all orientations. not sure why it didn't reassemble the same, but i'm sure i didn't hurt it none