This section provides a visual representation of how the Spark Plug can look depending on how the engine is running. If the engine is running too lean, the spark plug can look greyish white. If the engine is running too rich the spark plug will look black, sometimes a glossy black if it’s really rich. The goal is to get a good dark coffee brown color on the spark plug, which represents the correct color on the spark plug itself, and assures you that the Fuel to Air mixture on your carb is set correctly. This will also help assure you get the most power and longest lifespan out of your engine. Use the chart below as a guide to determine the correct Fuel to Air mixture that your engine is burning. A very special thanks to BlackHawk Mechanic Mike Gambrill & Team Pilot Brian Matthews for putting together this information.