I've a 6.5hp B&S vertical shaft lawnmower engine. Nothing unique about it, other than a very odd problem. Rotating the shaft in the direction that its s'pose to run is the problem -- it sticks when you first start turning and its difficult all the way around. Its different than it s'pose to feel, the compression & other stroke effects are there but there's something else impending rotation. But when it reversed, turned in a CCW direction, its starts turning easy and turns smoothly.

Removed the beltdriven, self-propelled drive -- no effect. Doesn't look like the pull-cord starter thing either. Shaft turns straight -- doesn't seem bent. Can a bearing act this way?

I'm dumbfounded. I thought I'd ask before spending hours pulling it apart.

6.5hp..... ohv or flat head side valve? Sounds like the compression release.