RE: Smoking Fuel?
As others have said: if you add something to the fuel it will hurt the combustion process. You'll either lose power or crud up the plug (& piston/sleeve) or both. Smoke systems work by blowing kerosene, heating oil, diesel or mineral oil into the hot exhaust AFTER the combustion chamber. You could probably add very little to get some noticable exhaust without ruining the performance, but you'd have to play around to find the right amount.