[Fortay]

I recently changed the oil in my Scag TC (STC52V-691FX G200009 with 600 hours) and put in a bit too much oil, like half an inch above the FULL line. Stupidly, I just ran it like that as there was no white smoke from the exhaust. As I pulled it into the garage tonight, it idled roughly. Seems ok at full throttle. I drained the excess oil, changed spark plugs (they didn't look fouled) and changed the fuel filter. After doing all this, there was still no change and it still seems to idle rough. Is there anything else I should check?
Thank you.

 

[JoeRagMan]

I don’t know what engine is installed but it’s probably a twin cylinder. Is it possible that it’s only firing one cylinder? You can check by letting it idle and using insulated pliers and leather gloves, pull one spark plug lead off at a time. If the engine quits it’s either a bad plug, coil or spark plug high tension lead. Good luck.

 

[sidemouse]

You might've pulled a spark plug wire inadvertently while changing the oil too, if it was running good before then chances are the issue is minor, just have to find it.

 

[Fortay]

I don’t know what engine is installed but it’s probably a twin cylinder. Is it possible that it’s only firing one cylinder? You can check by letting it idle and using insulated pliers and leather gloves, pull one spark plug lead off at a time. If the engine quits it’s either a bad plug, coil or spark plug high tension lead. Good luck.

Both cylinders are firing--both valve covers were hot after I ran the mower. Thank you, though.

 

[Justin Hightower]

Probably bad fuel. Try a mist of brake cleaner in the intake while running and see if it smooths out

 

[AlohaMowing]

I don’t know what engine is installed

From the information OP provided, it is the Kawasaki FX691V, 2 cylinders, air cooled, with carburetor.

put in a bit too much oil, like half an inch above the FULL line. Stupidly, I just ran it like that as there was no white smoke from the exhaust. . . . it idled roughly . . .

Most likely it will be fine, it may need to run a bit longer. It seems highly unlikely that there is any fuel/carburetor issue, but if in doubt, or to do a little light cleaning inside the cylinders you might put some Seafoam in the gas.

But what I most wanted to comment on was the reference to "no white smoke." I cannot conceive of a situation in which you would see "white smoke" from the exhaust unless there was reason to think that water was in the engine or exhaust. One can do some diagnosis by the color of the exhaust. Black exhaust tends to indicate the fuel mixture is too rich. Blue exhaust tends to indicate oil is being burned. White exhaust tends to indicate water is being turned to steam. With an air cooled engine there should be no issue of water turning to steam under normal circumstances.