Not sure if this helps but on my oiler I run the Bst36mm carbs. Yours look quite similar.Yeah, I already rummaged through all my house, now looking for excuses to have the neighbors invite me in :shifty lol. My daughter suggested hitting up the beading section at a hobby store as they use small bits like that, if I get time this weekend I'll give it a shot. I had planned on changing the float and cap screws all along for ease of maintenance, but also did the rack mounts because every single one of them stripped first try, it's like they make carb screws out of butter. Got excited to get the motor back in the cradle and had my son help, we got the motor jacked in place and the rear bolts in when I realized that the airbox was still sitting on the bench:banghead. Made for a good stopping point for dinner at least. That stupid air box is huge.
If you want I can get the measurement for the washer if you like???