Ive found my bottom cylinder always smokes alittle more than the top when I first start the bike. Ive always put this down to any oil thats in the crank case will run down into the cylinder. On first start up it will smoke untill this excess oil is burned off.

If it smokes all the time then we really need to know what pre mix you are running. HRC recomend 30:1.

I had a feeling your 16 was all stock though so are you sure your oil pump is adjusted right? Or are you pre mixing and using an oil pump?

If you are using an oil pump and its adjusted right then I would look at maybe doing a compression test and then have a look inside.
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If I have to take the carbs off once more...