Is there any place on the Internet where I can see pictures of spark plugs and
learn how to read them?
I don't know of such a guide so I put one together for you, of the five
popular spark plug patterns for two-stroke engines.
This plug has heavy carbon build up. This engine had a blown
crank seal on the tranny side of the crank. Tranny oil entered the crankcase and
was burned in the combustion chamber. Engines like this will billow thick blue
smoke out the exhaust pipe.
This plug is wet fouled. The spark plug's heat range is
either too cold or the carb jetting is too rich.
This plug has a shiny appearance. The engine had a problem
with air filter sealing. Sand entered through the filter and into the engine.
The high combustion temperatures caused the sand to melt and form glass around
the spark plug.
This plug has tiny globs of aluminum packed around the
insulator. The engine suffered a meltdown from ignition timing that was advanced
too much. The heat could not transfer from the spark plug fast enough and the
center of the piston melted causing the molten aluminum to collect on the plug.
This is a perfect plug. The color is mocha brown so the carb
jetting is optimum. The first three threads are black signifying the plug's
heat range is matched to the application. There are relatively low deposits
considering that this engine was run on regular pump petrol.