Due to ethanol in the gas I needed to clean out the petcock as the On was partially blocked (still flowed well) and the Reserve was almost fully blocked with very little flow.

Once I finished cleaning out the ports, it seems the way it goes together would not provide such a good seal. Can I get confirmation on the ordering of the parts, especially the wavy metal washer against the orange seal. I have it laid out the way I think, such that it would fit together from left on bottom to right on the top.

The spring washer goes on top of the tap part underneath the fixing plate, its what gives it pressure to seal. ;-)

Looks to be the same as early yamaha ty seals.

A good tip if your not used to working on bikes is to take photos of parts as they come off.

I agree with everything you have said, I even usually do take pictures just forgot for this one.

The ordering you suggest is what makes most sense to me also I just thought it was initially placed were it is now but as you mention it would seemingly not provide a seal.