General B&S Question

[plpitts1]

Where I work, I would say 90% of our repairs are bad gas/gas left in mower and gas relaited issues. We take off the carb, disassemble, clean and put it back on and all is good. I have noticed that on some of the Toro Recycler’s with the Briggs and Stratton engine, that after we get it running it seems to miss or hiccup about every 30 seconds or so. It does this when there is no load. Other than that they seem fine. Doesn’t matter if we clean 1 or 3 times in an ultrasonic cleaner. Would this be normal? In some cases we have replaced the plug, set RPM to spec, make sure it has clean filter, and we always use fresh gas of course (same results). I guess I am directing this toward a certified Briggs and Stratton Tech. I do not have a particular engine model, this is just a general question if there is such a thing.
We are striving to get it right, but this little bug we seem to not figure out.
Thanks,
Pat

[Az Shadeguy]

I have run into to this also Honda, Honda clones and Briggs.
Sometimes its cheaper to replace carb.

[Deere2me]

Where I work, I would say 90% of our repairs are bad gas/gas left in mower and gas relaited issues. We take off the carb, disassemble, clean and put it back on and all is good. I have noticed that on some of the Toro Recycler’s with the Briggs and Stratton engine, that after we get it running it seems to miss or hiccup about every 30 seconds or so. It does this when there is no load. Other than that they seem fine. Doesn’t matter if we clean 1 or 3 times in an ultrasonic cleaner. Would this be normal? In some cases we have replaced the plug, set RPM to spec, make sure it has clean filter, and we always use fresh gas of course (same results). I guess I am directing this toward a certified Briggs and Stratton Tech. I do not have a particular engine model, this is just a general question if there is such a thing.
We are striving to get it right, but this little bug we seem to not figure out.
Thanks,
Pat

If you're talkin about the L head series, there's a couple of things to check/try. Is the intake tube tight on the cylinder, check it for cracks also. I always smear a dab of grease on the carb/tube O ring. Also I usually put a drop or two of motor oil on the throttle shaft seal, does two things: helps to dampen the movement and also seals the shaft somewhat. Also I usually will pop the emulsion tube out of the carb when I clean em. It's pressed in and " not removeable" but you can stick a large flat blade screwdriver in the venturi and pry down, it will pop free. I usually use half of a spring type clothespin or popsickle stick to protect the nozzle.
Also, I have heard that if the teeny tiny hole in the center of the bowl nut is opened up just a scosh it seems to help the overall performance. Have no idea how it works.........
Could also be a sticky valve.

[KE4AVB]

Also, I have heard that if the teeny tiny hole in the center of the bowl nut is opened up just a scosh it seems to help the overall performance. Have no idea how it works.........

Deere2me, Maybe hmmm because it is the main jet. A number drill bit one jet size larger would be best if you enlarge these jets as too much then you will have the engine running rich.

plpitts1, It probably help we could get idea of the engines your experiencing these problems on and what type gas tanks if rider type equipment. Could be as simple as the wrong plug installed.

[bgsengine]

Also, I have heard that if the teeny tiny hole in the center of the bowl nut is opened up just a scosh it seems to help the overall performance. Have no idea how it works.........

Deere2me, Maybe hmmm because it is the main jet. A number drill bit one jet size larger would be best if you enlarge these jets as too much then you will have the engine running rich.

Could be he knows that but just covering his butt with the EPA.

[Deere2me]

No, really, I don't know nuthin'....this IS my first rodeo!
Gotta go......I see a plain lookin' SUV with blacked out windows pullin in my driveway!

[HondaG100]

Sad that the government makes everything their business. The older Honda side valve engines that I work with allot seem to all do this. I am certain it is a leak somewhere but it's likely not always in the same place. I just rebuilt a 2.5 that did what you described but it mostly went away after break in which may indicate that I had a valve not completely sealing.

[plpitts1]

Toro Recycler Model 20333, Engine #128M02 0001-f1 12101758, Manufacured Oct. 2012.
Apologize for the no numbers. I was shooting for just a general question, I know better. It just seems odd to me that we do not have this trouble with other Engines. It looks like my Question was answered. It only does it at idle no load, never when under load. The question was is this this acceptable, or am I doing a poor job cleaning/adjusting. By the responses so far it appears that this is not ok.
Thanks,
Pat

[creia]

It just seems odd to me that we do not have this trouble with other Engines.
Thanks,
Pat

Pat,
We are experiencing the same condition you described right now on a Tecumseh HM-100.
Michael

[bgsengine]

The question was is this this acceptable,

Judgement call- For some customers, they may never notice or care. For others, it's a major issue. The simple fact is, emissions carburetors are built to run lean, the fact that you only see this on this one particular engine type code may indicate that the carburetor itself is possibly unique to THIS ENGINE. So, to really look into whether this may be an inherent issue to this particular spec, one would trend to look up the carburetor for model fitment, and find other engines that use the carburetor and see if THOSE engines experience the same issue. If not, then maybe look at the Top No Load RPM spec between those engines - see if that varies - Could be it just happens to occur at a particular narrow RPM Band where the particular governor spring is holding the engine at the speed it seems to have the problem, if that seems to be the case, perhaps try adjusting the top no load spec a little bit down (or up, but that's a little dangerous) and see if the problem goes away or lessens, which would indicate it is just something specific to the engine design and emissions certification that happens in a specific RPM range, and that would be just something specific to that engine design...

or am I doing a poor job cleaning/adjusting.

No matter how good a job you do, there's always some areas where you just cannot get them clean, period.

By the responses so far it appears that this is not ok.
Thanks,
Pat

It is a judgement call - if you can fix the problem by ONLY putting on a new carburetor and no other changes, then you know the problem is the carburetor, and may just be one of those that is impossible to get perfectly clean, and has no room for deviation. But if a new carburetor results in the same issue, it may very well be just something specific to that engine spec or design.

On the other hand, it could be as simple as changing out the spark plug for a *different brand* , or a new plug, or adjusting the gap a little smaller or a little bigger - sometimes it takes only a very tiny little change to make a problem like this go away. - Emissions engines have very little room for error because there's few, if any, adjustments to them - so if something changes in any one system, then other adjustments may compensate.. or not.. Have a number of Tecumseh VLV riding mower engines that as they age, seems like just a slight bit of wear in the throttle shaft or bore allowing a tiny air leak causes them to have a pretty serious surge issue at top no load... only solution is carburetor replacement, or if you care to take your chances getting caught by the EPA, modification of the carburetor.