I think Dauntae's post is good. No, it can't possibly address every situation, BUT...
It provides a logical process for initial adjustment of any glow engine and this process
is indeed rooted in fact.

It's AFTER this basic process has been accomplished that we can make clear
assessments of what further, "fine-tuning" adjustments are needed. This
fine tuning will be highly engine/prop/fuel/plug/installation dependent. In this
case, no off-the-shelf procedure can replace careful observation and adjustment.

Good stuff Dauntae.

'Race