How do you get it to smoke? What do you put in it?

re-check the valve timing marks

black smoke is gas is running to rich,,, blue or gray smoke is oil burning.. did you overfill your oil ? if you didn't change the filter you may have too much oil in now..

corroded terminals maybe

since you've replaced the map sensor I'll assume you're dealing with black smoke. a bad coolant and/or intake air temperature sensor could create black smoke, also a bad injector could do it, especially if it's monopoint injection.

Did you put in 2-cycle mixed gas? If putting gas in it was the last thing you did before it started smoking then I would start there. Oil causes smoke and there's only 2 ways oil can get into the cylinder; mixed with gas or bypassing the piston rings. Lets hope its the gas.

white smoke is water lite blue or black smoke is oil. Replacing the main bearing would not cause it to smoke, Could be eather a bad plug not getting fire or oil fillen, or bad ring's good luck to you.

It's possible you overfilled the power steering reservoir or perhaps spilled some that leaked down on the exhaust manifold. That would cause a lot of smoke until it burned off.

yes sounds like it, take your sparkplug out and clean or replace it and crank engine over a few times to blow out any oil in the cylinder

sound like your valve seals are goin. I wouldn't worry about it until it starts smoking alot more and burning alot of oil.