Funny story here,I got them from SICK BIKE PARTS and I also put one where the throttle cable hooks up to carb in the screw cap it is the same diameter
I went on the quest of finding these elusive #113 "O" rings from every 2 cycle sales and service, hydraulic sales and service, automotive stores, automotive repair shops, Western Auto/True Value Hardware stores, you name it i searched it, IN PERSON as well as asking store personel...Their was exactly "ONE", single, #113 gas/oil resistant "O" ring in all of Alamogordo NM.
PLEASE, post me URLs of any and all suppliers of these gas and oil resistant "O" rings so i can buy a bag of these suckers...Someone could make a killing on the re-sale market on these suckers if they are as hard to find as what i found, or more correctly, only found one...lol...DAMIEN