Its never smooth when there is no prop unless the engine has been run before and there is no glow plug. Put on a prop and you will see that the smoother feeling comes from LEVERAGE. Still the engine will feel a little tight at Top Dead Center, the sleeve is pinched at the top, means the top has a little taper I believe.

Put the engine on a bench, use something like a 10x6 or 11x5 prop to run it in. There will be conflicting views on how to run it in, so I will not comment. For me I just let the engine run slightly rich for one tank then take her up on a just a little rich setting for a few tanks then start to lean her out a bit. During the first few tanks I do not push the engine too hard ... neither do I just putter about.

My TT46 starts with a back flip, just spin the spinner. No need for an electric starter ... also its inverted. Just come care and affection will ensure happy running of the engine.