I repowered my nephews' minibike with a 79cc HF Predator engine. My father was building a twin-turbo 632ci BBC for a customer while I borrowed some workspace to swap the engine. I took the liberty of giving the HF engine a full teardown for inspection and re assembly. We gave the head a light port and polish job. And used some left over Cerakote coatings on the head, valves, and piston. The piston top, combustion chamber, and valve tops received V136 thermal barrier coating. The valve stems and piston skirt received C110 micro slick dry film ceramic coating.
Okay the oil change:
Out: Rotella T5 10w30 (5 hour break-in)
In: Rotella T6 5w40
Top speed 38 mph with me on it, 225 lbs, GPS.