9 times out of 10, a new engine will smoke when first started (smoke externally0.
this is because the engines are covered in a light film of machine oil to protect them while they sit waiting to be shipped.
If you are getting sparks out of your exhaust, it could be loose material in the pipe that is falling off when it gets good & hot.
This is not uncommon because the chinese welding process isn't as good, and there will be lots of slag (debris) left over from the welding.
If the sparks are coming from your exhaust externally, it can be the same thing...welding slag.
but if your pipe is getting that hot, you may have a fuel-air ratio problem..running too lean.
but since you don't know anything about these engines, that may be too in depth right now.
you are mixing 2 stroke oil into your gas at a ratio of 16:1 or 20:1 right?