stoopid B&S 125K02 walbro carb sensitivity

[Quest]

got a freebie craftsman mower with a B&S 125K02 on it (5yrs old). Owner dumped it (on me, I'm da "recycler") due to hard starting, smokes, etc. never changed the oil, tune up, etc. for all these years.

still on factory oil (judging by the giltters in the oil), air filter is clogged, walbro carb bowl is in good shape (with a bit of water), spark plug all carboned up due to excessively rich fuel/air mixture (this one has a primer bulb but no choke, no speed(hi/low) adjustments, etc. supposedly a one-tug start deal). cleaned the jets, adjust carb, etc. got it to starting consistently with a fresh champion plug I have in-stock.

Put in the original air-filter (still pass light-test, but plugged with dandelion seeds,etc.) the engine popped once with sooty smoke in the exhaust and then died...never start again...
took the air filter off the housing, tug it once, and it fired up right away...

Observations: these walbro carbs are very sensitive to air-filter conditions: if the condition is poor, it will absolutely refuse to start. Unlike those old pulsajet varieties (with the foam cleaner, which I never have any trouble with)...

Q.

p.s. just drained the oil from the engine, re-filled with some recycled German castrol syntec 0W30 (from my previous experimentation on my 07 fit)...baby runs smoothly now..

 

[mechtech2]

I have had grief with those totally non adjustable carbs.
E10 fuel makes things worse - they were designed and orificed for pure gas.
BTW, there should be an automatic choke - a lightly spring loaded flap that goes away with any engine start.

 

[Quest]

This engine was built to Cali emissions spec (I believe it's written as 2005 or 06 spec).

Just bought a fresh new air filter (491588s) and will see.

BTW: these carbs/engines are already spec'ed for E-10 gas (we've been on E-10 for over a decade, so all engines be they large/small, are already on it).

Gonna run the engine hot again before draining the crankcase and then put in some Chevron DELO 15W40.

Q.

BTW: I know there's a choke-like flap inside the carb.

 

[Quest]

**final update**

a fresh new champion EZstart plug ( have a few on hand, for I regularly service B&S mowers), a fresh air filter, and voila! the darm thing started right up, consistently.

Rinsed the plastic fuel tank with fresh gas (rinsed out all the water residue at the bottom), shampooed the engine to rid of all the oily buildup, etc. washed the deck and the wheels a bit, and now I have a5 yr old B&S mower ready for the season!

need a new 21" high lift blade replacement, a 150 micron 1/4" fuel filter (75micron is fine also, but hard to get in my area) and then I'm all set.

Yes, as much as most posters/owners hated these walbro carbs, I, for one, am fond of it due to it's simplicity (an overhaul gasket kit costs 6 bux online and can get it up and running nicely, as opposed to a cruddy pulsa-jet carb assembly, which, by and large, difficult to get it running right once they crudded up).

Q.