Changed to a 525 size chain and sprocket setup and because of the thickness difference on the front, now the nut doesn't tighten the sprocket.

Looks like I need another washer maybe? What side does the washer go on?

Has anyone else ran into this?

Fixed it by taking a washer that was large enough to fit the splined output shaft, the had it milled to .020" the medium difference between the (2) sprocket thicknesses. I was then able to torque the splined shaft.