Heck,
I nearly broke all engines I laid my hands on. Better is the NME of good, but you cannot define the border if you do not cross it.
In the process you learn a lot while paying dues.
While tuning MX engines, I did not know and just fumbled in the dark. Yet my engines performed very well and did finish the race most of the time if the rider did his prepatory work. Wish I could turn back time.
ORIGINAL: Kweasel
When I was asking these kinds of questions, Duke Fox said to me "You are about a dozen ruined engines away from from figuring out what works really good". He was right.