SX200 Carbon Emission

Hi,
When running, especially on a long journey my engine, Legshields are covered in like a black carbon dust, any ideas?
I am running a Mugello 225 kit and and 30m Carb
When running, especially on a long journey my engine, Legshields are covered in like a black carbon dust, any ideas?
I am running a Mugello 225 kit and and 30m Carb