A friend brought me an old push mower to see if I could get it running. Been sitting. Usual first test, spray some carb cleaner in it and it fires up. carb is similar to this one.
http://outdoorpowerinfo.com/repairs/tec ... 632795.asp
So I do the usual cleanup. Only the hole in the nut plus the air passage. Nut has .065 on bottom and .065 cleaner fit in the hole. It needed new primer bulb. Get it back together and still problems ,it runs only on the prime and stops. Finally after adding carb cleaner squirts it would stay running but not smooth. Not your normal lean surge. I thought that it was running rich (but no black smoke) because rpm would drop if I added foam air cleaner. Usually that would help a lean condition. Thinking of the rich aspect I removed and further worked on the air passage to centre post that atomizes the fuel. No change. But while running I then 'dribbled' carb cleaner into the air intake. It would run fine. Stop and it went bad again. It was repeatable. So I looked up engine and found carb number. Looked up carb and found part number for the nut/bolt/jet. I had one . Pulled it out and it had the same .065 on it but when I checked with my cleaner prods the .075 would go in. Put that one in and it now runs decent. Does seem to need a lot of primes to get it going.