The best thing to do is to scrub it , but don't scrub it too hard.
Bam!
It is on the neck of the Kawasaki i think.
gone or remove
Use vinegar and rud it on the dirt for about 1 minute or less until you see the dirt come off then wash your neck
(Some people have dirt. So the black stuff in peoples necks is DIRT! ) A classic logical error above. Because 'some' people "have dirt" does not mean that the black stuff on various unspecified people's necks is dirt. The black stuff could, for example, be oil, or ink. In any event, the questioner wrote "on your neck". Grammatically and logically this can only mean the neck of the person to whom the question is directed. Because it is not possible to generalize about all people with black stuff on their necks, the original answer, "There is no black stuff on my neck. You must be looking at someone else." makes more sense.
You will find the VIN number in the neck of the frame. Engine number, the vin is on the neck but as a dirt bike it may not have an engine #
Take baths regularly.
Use rubbing alcohol.
The need for them to have a long neck is gone? All the tall tree food sources become extinct and they only need to eat plants from the ground.
It should be on the front or bottom of the frame, or it might also be on the neck.
BANG. and the dirt is gone :)
look at the numbers on the frame and call your dealer they can tell you . there on the goos neck