Red glowing S-header

The sooty looking plug is from the LEFT cylinder. The lean mixture is on the RiGHT side where the header was glowing. It was visible at daylight. I will make a compression check to see if the outlet valve closes correctly. If that is okay I will adjust the carbs once more.
Whish me luck for not pulling the head again.

rivera said:

The sooty looking plug is from the LEFT cylinder. The lean mixture is on the RiGHT side where the header was glowing. It was visible at daylight. I will make a compression check to see if the outlet valve closes correctly. If that is okay I will adjust the carbs once more.
Whish me luck for not pulling the head again.

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It looks like the right side is running correctly. It is carrying an extra load as the left side is not running correctly. That will cause extra heat which may make the pipe glow easier.

You need to be looking at the left side for carb problems, compression problems or cam problems.
[or maybe something as simple as a bad plug] Jim

Are you burning oil? At least more than you think you should. A couple of checks are to look down the intake when you take the carbs off see if there is any oil deposits on the valve, compare both.

The other check you can do is take the plugs out, spin the motor over very slowly with an ear close to the plug hole and listen for any sounds of a liquid being sucked/blown through a small orifice type nature.

Then try with a valve cover removed, if there was a noise, it should no longer be there as any pressure goes to atmosphere.

If it can be heard on the side with the black plug it might be oil getting blown through the valve guide as the cylinder head pressures up. Oil in the mixture will, I think, give a rich mixture as less air in the burning process.