oil level

What is the correct oil level in UL oil tank.
My dipstick has only two markings. "danger" in bottom end and "Refill" closer top.
No other markings.
Usually its good to have air space over oil level (in british bikes which I am more familiar to).
So how much over refill mark (or under filler hole) is good?
Service manual only says "more oil, better cooling..."

At the refill line you can add a quart. You need to leave the level just below the return/vent line fittings.

Thanks for that info.
I had about half quart over refill mark (did not want to overfill)

Long project ,total overhaul, behind and doing running-in.
seems to working OK,,partially thanks to this FP-tech talk.