On Sat, 14 Aug 2010 08:18:44 -0700, hr(bob) wrote:

On Aug 14, 9:13Â*am, Jeff The Drunk wrote:
10 years old, replaced the carb in 2006 at the suggestion of a Lawn Boy
repair shop. Original plastic carb, throttle shaft sticks disabling the
governor. New carb was redesigned supposedly to cure this but 4 year
later running into the same problem. The plastic carb is warping when
tightened down making either the butterfly stick of the shaft or both.

Temp cure is to loosen the mounting screws (two philips heads) to free
up the throttle shaft so the governor works. That allows it to be used
but the engine revs back and forth telling me the shaft is still a bit
sticky. Any looser bolted to the motor and it will suck air at the
gasket and not run right.

What to do...

Option 1, sand the carb flange with 1000 grit on a flat surface to make
sure it is flat (like milling a car motor head) ? Over-bore the
throttle shaft ever so slightly so if the carb flange warps when
tightened it won't seize the shaft? Widen the venturi around the
butterfly so if it is seizing when the carb is tightened it won't
seize? All the above?

I'm tired of ****ing with this POS. My kid mowed this morning and
except for the wide open initial rev (2 seconds) when started and the
govenor oscillation when there is no load on the motor, it actually ran
well. But i know as soon as it sits for a while, maybe a week or two,
I'm going to have to **** with it again.

Your thoughts (besides buy a new mower);

Can't you make a gasket that will have the inverse irregularities?
Sounds like a few layers of paper judiciously placed might do the trick.
Also please clean up your language...

Don't grammar-cop my language #1.

Paper would likely never stand up to the heat of the motor. The problem
is that the carb is plastic and has warped. There are several approaches
to modding the carb to get a few more years out of it, I described most
of them. I think what I will try first is widening the venturi around the
butterfly by a .001 or so. The butterfly slides through a slot on the
throttle shaft and is held in place by three indents in the butterfly.
Too small to use screws I guess. The throttle shaft itself seems loose
enough when the carb is off so I doubt the carb flange is warping enough
to effect it. The butterfly and shaft are about 1 or 2 mm behind the carb
outlet flange so they are really close to the motor.