carb cleaning-black carbon

[terrylee]

Have been tearing apart carbs on 80 850 and cleaning and replacing o-rings. They weren't to bad, except number one and some black dust(carbon) inside top of carb, and by butterfly valve which looked like dust on end of sparkplug when running rich. No dust in the intake boot on engine. Was i just running too rich on that carb. or is it a sign of another problem? terrylee

[tkent02]

Likely your valve clearances are too tight, causing backfiring through the intake. Adjust them properly before you burn some valves.

[terrylee]

Will do, has been about a year since I checked them. Was planning on doing it before putting everything back together. terrylee