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I have a 2009 LA 105 John Deere Riding Mower Briggs Model 31P677 Type 0140B1 with a 19.5 HP engine The engine runs decently under load at 3/4 to full throttle. However, in no load neutral or low speed the RPMs are too high I attempted multiple times to adjust the idle screw with no improvement. Please advise.
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See page 8, Carburetor & Engine Speed in Operators Manual.

mechanic mark said:

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www.briggsandstratton.com

See page 8, Carburetor & Engine Speed in Operators Manual.

ARIMain - GREENPARTS

Buy Genuine OEM John Deere parts for your John Deere LA105 Tractor Material Collection System -PC9740 carburetor: fuel & air and ship today! Huge in-stock inventory of OEM John Deere parts.

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The manual enumerates that the carburetor is non adjustable. However the Nikki carburetor has a main jet plus low speed idle screw. The Manuel mentions a carburetor computerized setting. Please advise.

You can purchase a rebuild kit for $72.00 or new carburetor for $132.28.

Are you using a tachometer to check the idle speed or just going by ear? The spec'd idle speed is 1750 rpm.

Here is the adjustment procedure (must use tachometer).


Also if it is a Nikki then the 796184 carburetor repair kit is listed at $58.00. And 591734 complete carb is listed at $119.00. An after market repair kit is dirt cheap for this carburetor.

Additionally, I have been gauging the RPM by ear since I have no RPM measuring device. However after 40 years of working on small engines a racing engine appears obvious.I will try bending that spring tang for low RPM adjustment.Thanks

It getting to where a tach is necessary on these smalls engines especially on the Briggs v-twins and many of the handheld equipment to tune the carburetor.

But if the engine is racing off load then it is likely either a static governor adjustment problem, a failed governor, or a weak/missing governor spring..

if you have a smart phone I think they make an Engine RPM app that analyzes the frequency.

I use one of these on small engines https://www.amazon.com/Briggs-Strat...ocphy=9032549&hvtargid=pla-320880335015&psc=1

Do you or anyone out there have a suggestion for a reliable, durable, quality aftermarket carburetor? The OEM Briggs replacement AUC 11044 has a non fitting solenoid connector.

First AUC11044 is a John Deere part number for the Briggs 591734. You paying JD markup on the Briggs part. Search using 591734 will come multiple after markets carburetors; just no guarantee they will be right operating wise as many after market are junk.

I do have a couple questions. What is the problem with the connector? Did the old carburetor had just an one wire connector? If so you do need install the upgraded connector for the two wire solenoid as Briggs did away with the one quite some time ago. The new harness may need some mods to be installed. Here I make up my own but I have the necessary electrical on hand along with the correct crimper.

The Briggs OEM carburetor sells for a mere $170. The Chinese knockoffs are marketed for $15-$25. Unfortunately, barring obtaining a used OEM carburetor, no middle ground exists.

Evidently you did not see first post after your initial post, $132.28. Click on Green Parts & scroll down page, carburetor is first item.

I actually discovered the 581734 Briggs carburetor locally for $126 Surprisingly, they are a bit cloudy on a warranty, reluctantly giving a meager six month guarantee. In contrast the $13 Chinese knockoff grants a 1 year warranty. LOL

Additionally, is there a Walbro carburetor which may be substituted for the Briggs 581734?

Syconeer 594603 Carburetor for Riding Lawn Mower Tractor Carb Fits Nikki Replace OE 594603 591734 796110 844717​

This $17 Syconeer aftermarket carburetor featured by Amazon,has no main fuel jet. However after trying 4 other carburetors this model idles perfectly, runs well under full load starts effortlessly and works flawlessly at all speeds in my 19.5 hp Briggs engine on a 2009 Deere LA 105 I may have gotten lucky. I suspect the main jet is tailored for the 19.5 HP Briggs as opposed to the other more generic carburetor models

A carb is a carb is a carb
If the main jet is too small it will just run out of power under full load
The main difference is the leverage at the throttle rod so the position of the butterfly has to be in sync with the movements of the governor
I have at times drilled new holes in the governor arm so the full travel of the arm coinsided with full opening of the throttle butterfly .
After that it is just the size of the carb throat ( venturl to be precise )
Too big and the response will be sluggish and too small will make the response to violent
However there is a big range in between the extremes where you will get acceptable to perfect running .

My surprisingly well functioning aftermarket carburetor features no problematic adjustable main jet like the Nikki carburetor it replaced