diagnose output port condition, carbed 6 gurus Options

[mskala]

Just getting to the valve adjust on the 914-6, found that
#4 and #6 output ports look different. #5 + all the right side,
are just carbon like from idling rich. What does #4 and #6
look like to you? Thanks for any help.

Cyl #4

Cyl #6

Others

[Carl]

Mark,
Explain the "Black Magic" comment. You can't get the screws to turn? If they turn there's no response?

The most common result of lean idle jets is a stumble to the engine on acceleration and spitting back through the carbs at idle.

What do the plugs look like?

I agree with your question about the oil in the exhaust ports. Ordinarily you'd be trailing smoke with any significant quantity of oil leaking past the exhaust guides and you'd see carbon in the port. So, it could be lower temps in those cylinders due to ?? guessing here -> can't be running lean since that's hotter and oil would burn so, maybe these cyls are running rich and the oil is providing enough of a coating that the carbon is not sticking to the port walls they way it is in the others?