Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
I haven't started any of my 500 engines for over 30 years, so no chance of looking. I do have a few spare crankcases lying around, next time I see one I'll drop some fluid down the oil pump outlet and see where it comes out.I remember the oil filter bolt quite well, certainly remember the way the valve was held in but never had the need to remove the valve. I seemed to recall the spring is the first thing fitted, then the washer, then the filter not the other way round as you explain it. It was why most people lost the washer when changing the filter as you couldn't see it under the filter and the pressure used to stick it to the filter sealing rubber and got thrown away with the filter, that would make the valve being fitted just under the head of the bolt not near the crankcase. If my recollection is correct of course.
A few pics of 750 and 500. The oil leaves the pump and enters the oil filter housing on the outside. The oil enters the four holes at the top of the oil filter bolt.