Sounds like a fuel supply problem. Amazing that it runs for 30 minutes, then starts cutting out. I was working on a Craftsman rider, single cylinder about a month ago. Except his mower wouldn't make it to the 30 minute mark, only about 2 or 3 minutes, at other times maybe 5, then start cutting out and die completely,with the choke on. Even tho it was getting plenty of fuel, turned out to be a tiny piece of plastic on the plastic metering valve in the bottom of the float bowl cutting off fuel supply. You could look through the hole, squirt cleaner through it, all clear. But it would flop down and starve the pickup tube of fuel. Finally had to gouge it out with a wire and then everything ran fine! With your engine,something is causing it to starve for fuel having to use the choke. Thinking maybe a fuel pump going out? Check pump diaphragm for stiffness and being brittle, replace it. You could possibly do a bypass test on the fuel pump to see if it is the culprit but would have to put a gasoline tank above the carburetor and let gravity feed it. As per the fuel pump.. Check it for dirt and give it a general cleaning. Hope this helps.
