why does my riding mower smoke after I turn it off?

i know smoke can be caused from oil problems. also check your air filter and your choke and be sure its closing and opening. my lawnmower somtimes fires another sparkplug 10 seconds after it turns off but it runs fine.

Take the top off of the engine and make sure there's no grass clippings built up under it. A lawnmower engine has 'fins' for air cooling, if there's a mouse nest or other garbage in those fins then the engine can't keep itself cool and while the engine is still hot the garbage will continue to smolder or just burst into flames.

If it's just a little smoke coming out of the muffler it's probably just the exhaust from the gas getting burnt in the hot engine. With the key just being turned off the engine still does another full cycle but there's no spark to burn off that last drop of fuel. If that's the case, everything's good! But, I'd still clean out the fins, just to extend the life of your mower. When you're done mowing and the engine cools off, it needs all the grass clippings cleaned off of it (top + bottom) I got a small sprinkler that I park my mower on top of, turn it on and it washes the bottom of my mower for me!

I had my mower do this last year. I had put to much oil in it. It dont take much. I drained some out and cured the problem.

It's taking a smoke break? LOL. More than likely it's getting hot and or you have oil blowing past rings getting on the muffler.