I have a 1995 883 and I tore down the carb for cleaning. The towel with all the neatly arranged parts blew across the driveway, scattering my well-organized array, so I was left wondering about these two O-rings. One is for the accelerator pump housing cover (the cover that holds the diaphragm), and one is for the drain screw. Both are round rings of roughly equal circumfrence. the difference is that "A" is a true O-ring... donut shaped and slightly wider in circumfrence than "B". B is a round ring, but cut squarely instead of donut-shaped as if someone sliced tubing/fuel line.A would have to be stuffed into thecoverin such a way where it looks like it threatens tobind jump out, whereas thehard stretch of B over the drain plug would look as if itmight tearif I slipped it on the screw. Thus, I putB neatly into the pump housing and rolled Arelatively easily over the drain screw. the question is "didI switch these or not?" There are noindications in the manual and thedealership has neither in stock.
Again...
A

onut-shaped, slightly larger, installed on drain screw.
B: square-cut round ring, installed in accelerator pump housing.
(Note: we are not talking about that ridiculous, large ring that traverses the entire housing... these are the two small rings, smaller around than a pencil eraser.)