johnthunder

The reason for this is your carbs. The carbs have a tube in them called an emulsion tube. On large cylinder bikes the vibration from the engine pulling in the fuel makes the needles in the carb vibrate inside the emulsion tubes causing them to become oval. This then lets in more fuel and makes the bike run rich, this is why you have soot on your spark plugs and soot on your hands. Check your rear indicators too, I bet they are covered in soot. So, how do you cure this. You need to buy a new set of emulsion tubes and needles. These are available in kit form for this purpose as its quite a well known fault. It will cost you about £50 for the parts, once you have done this job, its quite a good idea to balance the carbs too. You will need some vacuum guages or you can make a manometer for free using some tube and a bit of oil and wood. After this your bike should run sweet. Mine had the same issue. The bike will run fine while running cold, and as soon as the bike is warm you will get really crap performance at low revs from it running too rich and choking the bike.