the spark plug should be light chocolate brown.
black and very oily means your too rich ... however too
rich is way better than too lean , which could blow the motor!
a lean condition would result in the plug looking real light tan or white
if you have a new plug.
a rich condition means more fuel than air .. if you haven't changed
the carb settings , then it could be your air filter is really dirty or the
carb air passages are clogged.
when messing with the carb
FIRST THING!
carefully screw in the air screw and count the turns of the screw
until you hit bottom and write it down so you can reset it right.
do the same with the idle screw.
for some good how to's go to utube and search for
how to clean a <scooter-moped- 2 stroke> carb.
oilyhans
i own a scooter shop with rentals ,sales& racing parts.
i also appraise scooters for KBB.
2003 Vino classic stage 0.75
de-reged stock variator w/8g sliding weights.
1.5k rpm springs
42mph
2005 veniceLX ~70cc~upjet~1.5k rpm springs & 7gr sliders
46mph
KeyWest de restricted~8gr slide