Ooops, looks like someone has been grinding away with an electric starter on it...
You need to check how much the crankshaft can move back and forth with the backplate on, you can leave the cylinder etc. off for this test.
Here are two images of the same motor, first when the crank is pull out as much as possible and the second when the crankshaft is pushed in as much as possible (and crankpin hits the backplate).
The washer will (or should) rest against the small ridge on the crankshaft, and as visible in the second picture this ridge should have to pass the front bearing surface before the crank pin hits the backplate. If you don't have a washer it still works as the propdriver will also rest against the same ridge.
I can't actually see any washer in your pictures above, I can only see a washer for the prop nut.
My engine didn't have any washer either but you will need at least a thin brass washer there if you want to use an electric starter, you cannot let aluminum grind onto aluminum in the front.
