AND I've found it to be a waste of time trying to use a generic oring. I've got several o ring kits and none fit.
Go by the part number.
In the USA I've bought them in 5 and 10 packs, even from flea bay. Just go to the dealer and expect some sticker price shock.
Also go to You tube for some good info about how to install the o ring onto the jet then into the carb (using a wire as a guide and some lube. The o ring will appear too small for the jet then too large when installing the jet into the carb.