Originally Posted by Agreen
Or carbon is giving you a "glow head" effect. Some RC airplane engines use a glow head, which is essentially a heated wire that glows white hot when a current is passed through it, then once the engine is running it continues to glow without electricity because the combustion makes it hot. Carbon hot spots can do that. Usually, they cause pre-ignition. That's really bad. And the carbon buildup can come from many sources, but mainly too much oil mix or an insufficient spark.
Sea foam is the cure to it run the sucker on high rev and dribble it in .Dont hydro lock it though