Carbs and black smoke Options

[pistonboy]

Hello

I moved a complete set of 44IDF carbs (complete with linkage and manifolds) from a 1.91 liter engine to a 2.73 liter engine. On the new and larger engine, black carbon is coming out the back. But it is not smoke. It is in the form of "soot" particles. Some are small and some are larger. I thought the jets were the wrong size but these carbs were producing clean exhaust on the smaller engine. If the jets were the wrong size, then there would be smoke, not soot.

The exhaust for the larger engine is a different system from the smaller engine. It is a used quad tip (Monza or Manta?).

Is it possible the soot is really carbon breaking loose from the interior of the exhaust system and has nothing to do with the engine? If it were the engine or carbs, it would be smoke, not soot.

What do you think? Has anyone had something like this happen with an old exhaust system?

Thank you.