BTW - Going from zero clearance to spec clearance 0.10mm was about 5/8 of a turn on each valve.
Loosen the nut, the small shaft on top of valve stem has a flat on it, a really skinny flat, none of my ignition wrenches were small enough, so I took a 4" crescent wrench and used that.
Yea, if I knew the tpi could calculate it precisely...
Of course check once tighten also, well I snugged it, then check, then tighten it, then check.
No torque spec I found in the GY6 manual, so just tightened it to a experienced good tight w/o stripping the nut, via 1/4" ratchet.
All ready for upcoming July 4th gathering at our home, as were ready for a Post Covid 19 big gathering
Got 5 nephews and nieces in 3-7 year range who will want rides.