What causes ashy spark plugs?

Heavy ash deposits on the insulator nose resulting from oil and fuel additives, in the scavening area and on the ground electrode. The structure of the ash is loose to cinder-like. Cause: Alloying constituents, particularly from engine oil, can deposit this ash in the combustion chamber and on the spark-plug face.

What does the color of spark plugs mean?

Light brown or tan colored deposits on the tip of your spark plugs are normal. If your spark plug is white in color or appears blistered, that means something is making the plug run too hot. Check for problems in your engine’s cooling, a lean fuel mixture or incorrect ignition timing.

Which is the best color for spark plugs?

You can use the burn color of your plugs and reference the plug color charts below to determine if your engine is running rich or lean. Good running conditions: If everything is good, the spark plug should have a tan/light brown color. Rich running conditions:If your engine is running too rich, the spark plug will be black and sooty.

What makes a spark plug Black or white?

Rich running conditions: If your engine is running too rich, the spark plug will be black and sooty. Lean running conditions: If your engine is running too lean, the spark plug will be white. If the spark plug is black and oily, they are oil fouled.

What should the spark plugs on a motorcycle look like?

Your motorcycle’s spark plugs can be very useful to diagnose running conditions in your engine. You can use the burn color of your plugs and reference the plug color charts below to determine if your engine is running rich or lean. Good running conditions: If everything is good, the spark plug should have a tan/light brown color.

What causes a spark plug to turn yellow?

Caused by over advanced ignition timing; poor engine cooling system, lean air fuel mixture, or a leaking intake manifold. When these conditions prevail, even a plug of the correct heat range will overheat. Glazing appears as a yellowish, varnish like color.