My 2001 c90 misfiring

[Nizcross]

Hi even when warm my c90 seems to misfire at low revs and black smoke like the choke is sticking and not fully closing i have cleaned all the carb out,new spark plug,oil change and cleaned the air filter

[barker]

was it running ok , and just developed this problem, or have you always had this

[Newtsalad]

If it's backfiring on the over run, it's the exhaust not sealed at the head.