1978 KZ400B rebuild. Resistants in crankshaft at the top of stroke?

Ive been working on rebuilding an old KZ400 during my free time for about 9 months now. I finally got around to taking on the engine. I've cleaned everything and started putting things back together. Ive noticed that the crank shaft feels tighter towards the top of the stroke when i turn it by hand. Is this normal? This is my first engine rebuild so I'm learning as I go.