Black smoke is a good sign on startup. it shows that the injection pump is over fueling the engine (which it needs to do in order to fire up and crank), the black smoke representing totally burnt fuel particles. White smoke, or 'clag' is also common, but this is usually the case when the injection pump over fuels on startup, but not all of the fuel is burned. Blue smoke would point to oil being burned, which they all do to some extent. It may be oil seeping down the valve stems into the cylinder, or it may just be drawing oil in through the air intake. Have a look in your air filter box. Is there any oil? The paper filter element should be dry and clean white (ideally). If there's any sign of oil, swap it and clean the filter box. The cyclone breather may also need cleaning out. that's the little black cylindrical catch tank that separates oil from 'blow by' before it is re-directed back through your air intake.
-Pos
