I recently purchased a 1985 Honda TLR250. The engine starts easy and idles nice. Just off idle the engine hesitates for a moment. When I pull the spark plug it is black and sooty. Carburetor information: Keihin 22mm, Main jet 100, pilot jet 38, slide 2.5, Needle position 2nd from top, idle air screw 1 1/4 turns out, spark plug DPR 8EA, plug gap .30", new air filter. My Question: How can I get rid of the hesitation just off idle and is the sooty plug a problem. Thanks for your help........Spongy