Walbro LMS for 6hp B&S mower surges

[LA1]

Hi I have a 6HP B&S with an LMS Flo-jet. It is the new kind w/o any adjustments. I also have a spare carb from another junker. Actually the B&S 6hp was a curb side pick up. I cleaned the carb new float bowl seal. The motor surges, tried the carb from the junker does the same. Slapped on an early LMS which has idle mixture adjust screw...dialed it in , runs fine. So is the engine worn past where it will work in the bounds of the new style LMS carbs? did I not do a complete cleaning?

 

[ILENGINE]

Surging indicates a partially clogged idle circuit in the carb. With todays new carbs with hair fine passages, mixed with the crappy fuel, you get corrosion that sometimes you cannot clean go enough to get them run correctly. Only option at that point is new carb. However short lived.