Can't figure out why honda 3011 riding lawn mower starts, runs for about 60 seconds under load and then stops. It will restart after 30 seconds and continues to do the same thing over and over. I've checked (cleaned carb twice), gets plenty of fuel, checked oil level, cleaned all filters. It seems to be heat related ? Please advise.. Thanks, John

Did you clean the fuel tank, and lines along with the carb? And you changed the filter correct.
I think you need to clean the carb again, and again if needed.

Cleaned carb twice - switched it with a good carb from a running honda 3811. Changed coils. Still does same thing.
Runs for about 60 seconds then bogs down, will restart after 30 seconds. Seems to have trouble under heavy load. I still think it is heat related.
Fuel line is clean, filter is new. Gets plenty of gas. Removed carb bowl screw and fuel flows great. Possible spark plug ? I'm at a total loss John

John, I got the same mower from my father-in-law and it did the same thing. He had disconnected the safety buzzer. Open the hood and look next to the shifter. You should see two places were wires come together into plastic clips. The one closest to the front of the mower goes to the buzzer. (You can see the wires going down to it) If this is disconnected or the wires are loose or pulled out of it, it will cause the problem you describe. I reconnected mine and it solved that problem. The other cause is if the seat shut-off has been disconnected. Lift the hood and up under it. You will see two wires with butt-connectors. Make sure these are tight as well. Good luck

Unbelievablel - new spark plug fixed my problem !
I had spent a lot of time isolating this simple problem - never thought a sprk plug would work until a certain temp and then fail. Great lawnmover, had this mower for over 15 years and it still cuts like the first day I bought it. So far I put new tires, batteries, greased steering column, and spark plug ! John