I know this is an old post, but I've got a Cal bike so I thought I'd throw in a suggestion. You can plug the far right and far left nipples. However, the far right nipple (facing the rear of the tank) is the tank vent, and if the tank has the original fuel cap it probably has the little o-ring installed which seals the fuel cap tank vent to that far right nipple. Check the exploded view of the tank cap assembly (See attached doc) and you'll find a CAL designation for the o-ring located in the tank cap ring which is attached to the fuel tank. The cap has a small pointy vent nipple which seals into that o-ring when the cap is closed. If you want to cap the nipple at the end of the tank, you have to remove the o-ring. The far left nipple is a fuel return line from the emission fuel return pump. It theoretically could also be used for a tank vent but if you drop your bike, I'd bet you would see fuel freely flowing out of it.