In olden times we could do a clean cut, read the plugs and re-jet
up or down depending. But then motor fuel had lots of lead in it and would give
you a color. A clean cut was from at temperature an a full throttle load,
ignition off and clutch in. So you were looking at the color of an operational
plug.
Today
we have no lead, and no colors to look at. So nobody looks at plugs anymore. If
you want to check for too high a heat range, check for cement boil around the
center electrode, and or flecks of porcelain missing.
The
light color with a plume of black is typical but usually the leading plug will
just look dirty. Even the end of the shell will be black. These plugs are not
the coldest plugs you can get. So long as the cement is staying out of sight,
these are fine. You use a higher heat range if you get fouling below full
throttle. You cannot hurt an engine with too low a heat range. You can destroy
it with too high a heat range. I use the coldest heat range made by NGK and
they don't foul. R6725-11.5 $25.00 each.
Thanks, Lynn. I’ll
probably run these another 20 hours and check them again.
Interesting; I buy these on-line from Rock
Auto in boxes of 4 for $5 each. The local parts stores want about double
that. I found them selling on e-bay for $12. Hum-m-m, looks like a
business opportunity.
Al