What's your problem? 17 hp ohc intek lawnmore engine wants to stall after running about 1/2 hour

change oil n filter plugs and fuel and air filter

It sounds as if a bearing or a blade on the deck might be frozen up or very stiff. Also check the belts on the deck as well.

Replace the fuel lines. I had the same problem with one of my riders. The inside of the fuel lines had rotted and they were collapsing when they tried to suck the gas through them.
New lines and it ran all day!

Running for 1/2 minute then stopping sounds like the carb's fuel bowl is starving for fuel. I would check the carb's float and needle and seat to verify it is not sticking. Usually when the engine runs there is enough vibration to unstick it. I would also look at fuel filter (disconnect the fuel line to the carb and verify that fuel flows freely - try not to spill too much).

How long does it run before it quits?

If you need further help, I’m available over the phone at https://www.6ya.com/expert/matt_8dbc24bf722649ac

Turn the motor until the piston is at TDC. Look through the spark plug hole. piston to top of the cylinder. Then set them like you would any OHC rocker arm. BE very careful with the exhaust valve adjustment. There is like a mini disc on top of the valve stem spring keeper. If you get it too loose on a vertical engine it can drop out and it will take you forever to find the little bugger!

Below is only a recommendation....

I don't know how many hours that are on this engine your working on but... I would recommend you hand lap the valves with grinding compound if you know it has high engine hours. It will make it easier to start and have more power. The exhaust valves on these engines get very noteable black gunk buildup in the seat to the point you can not see the "valve to seat" mating ring on the valve head. The heads are not hard to remove... (One at a time) just time consuming. It can be a chore getting the valve push rods aligned with the engine horizontal. Most of the time and I know good Mechs don't like to hear this.. you can reuse the cyl head gasket on this model due to the design. Once in a while they break not very often.

The valve springs have keyhole locks on the keeper.

Thanks for using FixYa,

Kelly

multi-grade will be fine it realy dont need a pricy oil in it this kind of engine will run on dirty cooking oil,,with or with out the chips still in it?

the carb is gummed up with laquer. take it of the motor and soak it in some solvent for an hour. but first take off the float cover before emersion.

sounds like its running too rich on fuel. try turning the fuel mixture screw in 1/4 turn at a time til it starts to stall then turn out 1/4 turn or 2 and see if that helps.Maybe when you used the air it turned this screw???

THE PROBLEM SOUNDS LIKE THE CARB IS RUNNING TO RICH OR TO MUCH GAS IS BEING PUMPED INTO THE CYLINDER. IS THERE ANY SMOKE AND WHAT COLOR SMOKE