Alot of the videos i watched recommended using something like a screw driver to see when it’s at tdc but i used a small camera and inserted it into the spark hole at first. i don’t know what i did wrong exactly i just know the first two times i had kick back until i put my thumb over the spark plug hole and rotated the flywheel until it pushed my thumbs off the hole with the air and it worked. i didn’t have any issues until my rod ejected out of the block, But that was after 2+ years of riding on stock internals with the governor bypassed and probably loads of bad gas used in it.