Motor ran fine in evening next morning black smoke, backfires and will not run above idle

SOURCE: Tractor wont start

For a small gas engine than won't start, think FAST -- Fuel, Air, Spark, Timing. You've replaced the filters and spark plugs and squirted in some starter fluid, eliminating the simple common fuel, air, and spark problems -- but I because of the backfiring I think your problem is in the timing -- like a sticking valve. Probably more than you want to tackle at home, but might not be as expensive as an engine replacement. Take it to a good small engine mechanic -- best bet is a lawn equipment shop that has been around many years. Drive a little farther to get to one if necessary.

SOURCE: My 24 hp 42 inch

Yes I would figure out who made the motor, B&S, Kawasaki, Kohler, Tecumseh are common. Go to their website, find your engine model number and get the valve clearances. Find a mechanical person in the neighborhood, avoid brothers-in-law, and give him a 12 pack of beer to adjust the valves for you. I think you will find your mower runs way better, backfiring will be gone. After 100 hours or 3 or so years you will note most of those companies recommend an adjustment. You most likely have a 2 cylinder and there are two small rocker covers near the spark plugs, Pull off the covers and the rockers will be exposed. Adjusting the gap between the rocker and the valve takes some skill and understanding of where the pistons are in relationship to the valve train and doing it wrong can be expensive. I know there are many videos on youtube if you want to take it on yourself.

SOURCE: Craftsman 26 hp Kohler engine 54

to be honest the enigne ahas a control that the left side must fire and run before the right starts to fire it sounds to me like you have a fuel issue possibly the carb. is gummed up and dirty.

SOURCE: Ran fine. shut off. will not start. tries but backfires

It could be as simple as a sheared flywheel key and/or the valves needing adjustment. The OHV engines that come in lawn and garden equipment these days are notorious for being very picky about the correct valve settings, especially single cylinder engines. Another common problem involves the fuel inlet valve in the carburetor. Not the solenoid valve but the float valve inside - if it doesn't seat properly fuel will overflow the carburetor and enter the engine. Several bad things happen after that - the cylinder can get enough gasoline in it to lock the piston when you try to start it and that can result in the aforementioned sheared flywheel key. The gasoline will also get past the piston and into the crankcase where it dilutes the oil and the result is poor lubrication. one of the first components to suffer from the lack of lubrication is the camshaft, particularly the exhaust valve lobe, which wears down to the point that it does not open the exhaust valve far enough and the exhaust cannot be expelled fully on the exhaust stroke. The leftover gasses then escape from the engine through the carburetor when the intake valve opens, sounding like a backfire but rather than fire coming out the carb you get popping and raw gas blowing out the intake. Check your oil for the odor of fuel. If it smells like gasoline and, perhaps is inexplicably overfilled with oil according to the dipstick, plan on having the carburetor inlet needle and seat replaced, possibly the flywheel key replaced and probably the camshaft replaced. Keep your fingers crossed that it is just the valves needing adjustment.