Carb tune-up?

[mbdownunder]

I have a Civic with the D15B4 (dual carb) and I'm sure it's running rich. I'm getting black soot on the back bumper and can smell petrol when it's idling at a red light. The air filter looks alright, but I'll probably change it soon anyway. Can I adjust the carbs to stop it from running so rich or is it one of those things that really should be left to a professional?

Thanks in advance for any advice.

Mark

[Edgeauto]

Could be a faulty choke assy, it the thing that's screws on to the L/H carby