pesky old tecumseh tvs90

[38racing]

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.

[KE4AVB]

All I can think of is that it may not be air tight on either the primer or the bowl seal.

As for jet size I had a Walbro earlier on a Powermate that I had to resize to about .78 mm when it was at .65 mm from the factory. I even try a new jet and had to resize to .78 mm or the engine surged constantly.

[Arkie]

All I can think of is that it may not be air tight on either the primer or the bowl seal.

As for jet size I had a Walbro earlier on a Powermate that I had to resize to about .78 mm when it was at .65 mm from the factory. I even try a new jet and had to resize to .78 mm or the engine surged constantly.

Been their on the Tecumseh and Walbro low emission also.

Did not really want to even mention it until I seen this, but I had to do the same just the other day to a Nikki carb on a single cylinder Briggs. Don't remember the exact sizes offhand, they are in my carb notes for that type carb.
I had cleaned the carb several times and all very clean and all the jet holes and I suspected the carb was for a 12hp engines and someone had placed it on a 15.5 because when I looked at the engine IPL a different type Nikki carb was listed and when I finally found the carb that was on the engine it was shown on a lesser HP Briggs engine, a very slight manual choke applied and all was good at idle and high speed and the .005 increase in the jet cured all. This one had a removable brass jet so as I could remove and play with the size's and re-solder/fill and drill back to OEM size if needed. I've also seen the low emissions Tecumseh's engines do real good doing such, but I make sure that the carb is real clean and all the jets passages have been probed first and intake, etc, double checked for air leaks.
Most generally seems to be about 2 sizes larger, but I always gauge first.