I I know I can't believe it was that low when I got it 😉 on a serious note I'm sure it was the ol' filling the bike on the side stand routine for the previous owner. I'm grateful it wasn't locked when I bought it. Yeah I found a PDF of the valves and I think I'll give it a go in the future. I hope I get some time to throw some of these parts on.I check & adjust the valves on each cylinder when both intake & exhaust valves are closed, it makes for a more consistent reading.
5.5qts?! Your engine is basically flooded, good thing it hasn't locked up.