[Superman]

Sometimes, but not always, when I stomp on the gas and run her up to redline, at about 4500-5000 rpm I get a curious event (I assume it's important to, ahem, clean carbon out of the cylinders from time to time). The engine crackles, sounds like pinging sort of, some power and smoothness is lost, and smoke comes out the back. This engine ordinarily does not ping, though ignition timing is set at 35 degrees full advance. Most of the time this event does not occur when I, ahem, clean some carbon out of the cylinders.

Since it does not happen all the time, and since the smoke phenomenon is part of the event, I am not ready to blame ignition timing. I wonder if carbon is getting loose and getting in there, or perhaps some oil gunk in the breather system is getting sucked in. Anybody have an idea what this is?