Can someone tell me if there are supposed to be two washers - one above and one below the fixed white plastic positioning ring (which has the clip right on top of it) on the stock needle - is this standard for a 2002 GS500 carburetor? 

I bought this bike used, and from parts fische diagrams cannot tell.  There is a thin washer above the clip and ring, and a thicker one below the ring. 

I'm wondering if the thicker washer below the ring is a shim that someone installed.....

I have a photo but don't know how to attach it... sorry.

I have the same set-up on my 2001. There is the thicker washer below the fixed plastic ring and above it a very thin e-clip and then a thin washer above that. I know that my carbs have been worked on b/c the plug over the idle mixture screw has been drilled out. The thicker washer does not appear to be accounted for in the Haynes Manual parts fiche. I'm not 100% sure though so someone else will have to chime in.

On a stock carb no matter what year, there are no washers where it counts.
89-00 - The E clip and under it is a tight spacer and above it is a larger hold down spacer. The spring sits on top of that.
The newer ones have the spacer under it and the washer on top of the e clip acts as a hold down washer and the plug with the spring etc goes on top of that. In some cases people mistakenly put that washer under ... maybe.
Cool.
Buddha.

Ok, thanks guys. 

Sounds like someone has been in these carbs on my bike and made some adjustments.  The thicker washer under the white ring does not sound like it was there stock, so that is a shim someone put in to richen the needle. 

My brass plug was also missing, so someone took that out, presumably to adjust the idle mixture screw (i.e. fuel screw), but the setting appears to be what is stock on that screw.  Also, the philips screws on the float bowls were a bit buggered up, so someone went in there - but the jets were all stock sizes.  Go figure. 

Always an adventure when you buy a used bike and start working on it.

Yea brass caps off = dead giveaway its been worked on before.

BTW the stock jets in there, sadly, dealer parts guys will recomend and sell jets ... same sizes as stock to people. WTF ... jets dont wear, and even if they do, its gonna wear the holes bigger so richer right. You can clean em all day long in literally anything, they are brass, impervious to everything ... and leanness wont be cured by the same damn jet.
You buy it with size and type, they are 4-5 bucks a pop. Buy it as a suzuki part with a suzuki part number (which the dealers do in a lot of cases) they are 15 bucks.

Cool.
Buddha.