Originally Posted by Wentwest
By this time I've forgotten all the story, but are your valve guides OK, and the valve seals? There's oil on top of the head that could be sucking in on the intake stroke, and exhaust could blow by on the exhaust stroke. That would put oil in the combustion chamber and exhaust in the crankcase. Your compression would be OK. The rings and bore would be OK too. You'd think the exhaust would go out the port and pipe, but there is some backpressure from a Honda muffler.
Guides look great, no deposits or oil starvation. Seals were just replaced after the first tear down and reassembly. Backside of intake
valve looks spotless, no debris or deposits in the intake port either. Exhaust valve was the gunky looking one, mainly on the valve face, and port leading out to the muffler joint, caked in sticky black soot. My newest theory was that exhaust gasses were slipping between the layers of the MLS head gasket and into the timing chain tunnel, thereby overpressuring the entire engine case, and maybe forcing too much oil up into the combustion chamber?