I opened mine up today to clean and rejet, noticed that only the mid jet has an o-ring, but not the pilot nor the main. Is this right? seems odd
I only found one o-ring in my 2007 carbs as well . It was dried, stiff and no good. Here's a link to my local dealer's parts finder.
http://partsfinder.onlinemicrofiche.com/montgomeryvillecyclecenter/showmodel.asp?Type=13&make=suzukimc&a=423&b=13&c=0&d=2007%20GS500F%20K7%20CARBURETOR%20ASSY.
My 90s carbs didn't have o-rings on either the pilot or mains.
Brass tends to be self sealing...