Has anyone tried the "Colortune" spark plug?
It's a spark plug, with a clear glass insulator, that allows you to
see the color of the flame in your combustion chamber.
Supposed to allow you to fine tune the mixture.
Too yellow is too rich. A rich, blue color, like a well-adjusted
oxy torch, is supposed to indicate the ideal mixture. Pale blue is
supposed to indicate a too lean mixture. I'm still perusing the 'net
for information. Some seem to swear by it, others think it's snake
oil.