[Known1]

I've always filled on the brake lever side of my bike, very similar to @Pauljp . Unlike him however, and only when the pump is forgiving, I'll top it off up the neck. If you don't have a forgiving pump, forget it as you'll end up with some gasoline spray on your tank. I've tried filling from the clutch lever side. That doesn't work for me at all and is very awkward.