94 1400 suzuki Intruder. 28000 miles. Started making some rattling noises while riding. Also noticed more vibration. Started missing. Changed plugs. Very black with carbon. Now misses very badly. Blows black soot out exhaust. Have I destroyed the engine.? I have been riding all summer in the mountains of west virginia. Lots of slow low RPMs.

have you tried a compression test? anything unusual in the oil? very poor fuel mileage?

Black soot out the pipes usually indicates a flooding carb, Would doubt you have a major engine problem.

has the carb ever been serviced?