1980 Kz750E Rear wheel too tight?

I have a 1980 Kz750E. I tore the whole bike down and cleaned it up to sell. When I installed the rear wheel I tightened down the rear wheel and when I do that the wheel gets really hard to turn. If I loosen it up its fine but obviously I can't run it loose. Any ideas?

So I checked my manual and everything was lined up correctly...collars, couplings, etc. The only thing that was different was the instead of threading the axle from right to left, I had to start it on the sprocket side because my exhaust pipe was in the way. Could this affect what happens when I tighten it down? Any help would be appreciated....thanks!!

You can put it in from any side. You probably have a spacer in wrong at the rear hub.

If you are absolutely sure you have all spacers fitted correctly, the only other thing that can cause this is if the spacer inside the rear wheel is too short - or the bearings not fully seated - causing the bearings to bind when under pressure.

Can you install the rear wheel & axle assy as a unit.

Thanks everyone for the help...and thanks Peter1958 for the diagram. It showed me that I had one of the collars in wrong. I reassembled it and its perfect!