So, a consideration to people who'd like to replace the oring with bike on the side. Either make sure the tanks are almost empty, or finish the job before the left one overfills the right one and starts dripping fuel. 990 is heavy enough to pick up without sliding around on the fuel on the ground :/ That being said, I've replaced the oring with a size that was slightly off, because that's what they had in store. It went in just fine, we'll see if it holds up. After cleaning the whole thing I'm actually not sure if the leak was the oil drain bolt or the sensor.