Small Engines (Lawn Mowers, etc.): Honda GX 120 Stalling

Question
QUESTION: previously engine ran rough and i cleaned out carb with wire and then the engine was running well. now it has a new problem where it starts on first pull and runs smoothly with no choke and then cuts out with out warning after ~8 minutes. won't restart immediately but if i wait a couple minutes it restarts and runs fine for 2-3 minutes and then cuts out again. each start thereafter only runs 2 minutes or so. if i wait a few days it will run about 8 minutes on first try again. Oil level is full and gas is clean and carb looks ok. it almost seems like there might be an engine temp sensor but i don't think there is. thank you

ANSWER: Have you replaced the spark plug with a new one?
Have the valve clearances ever been checked?
Eric

---------- FOLLOW-UP ----------

QUESTION: no and no but those sound like reasons that would cause rough running issues more than the intermittent issue i am having. i was thinking maybe some kind of vapor lock or engine kill switch or something with the electronic ignition. i did submerge this in sea water 3.5 years ago (it is a dive compressor) but hadn't had problems until this summer. i noticed today that the wire that connects to the on/off switch has chafed through so i taped it up and it made no difference.

Answer
I used to think the same thing about spark plugs but we see many spark plug fail...even in 4 cycle engines.

You cna check for spark as soon as the engine dies to help determine if the igntion module is failing.  Just have a know spark plug ready and when the engine stops dis-connect the spark plug wire and then connect the new or know good plug and pull the string to see if there is spark.  You will have to ground the spark plug tip of course but the should be a metal engine part in the area for grounding.

Use the address below to find the valve clearance:

http://outdoorpowerinfo.com/engine_specs/honda_valve_gaps.asp

Agree a valve will usually not cause this problem but the clearances are easy to check just to be sure they are correct.

Does the engine have a low oil sensor?

Eric