# toro 621e snowblower 163cc tecumseh carb needle valve



## rjk8619 (Jan 29, 2019)

*toro 621e snowblower 163cc toro/loncin engine carb needle valve*

There is a needle valve on the carb near the rear mounting plate of my toro snow blower. I have looked and looked and cannot find any information regarding this valve. Does anyone know what it is for and what it should be adjusted to. The carb part number is 119-1996 

Thanks


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## rjk8619 (Jan 29, 2019)

Aww come on, some smart person on this forum must know what this adjustment is for ????


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## LawnToro (Dec 28, 2018)

I have never seen one before. Possibly a mixture adjustment. Also, that is not a Tecumseh engine, or a Tecumseh carb. That engine is advertised as a genuine Toro engine, though it is actually made by Loincin.


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## paulm12 (May 22, 2015)

Yeah, looks like an idle mixture adjustment screw, but the newer machines usually do not have these, the mixtures are pre-set. On the older carbs, that mixture screw base setting was 1 turn out from all the way in (gently).


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## rjk8619 (Jan 29, 2019)

Thanks for the thoughts, I have corrected the tread title to reflect a toro/loncin engine. Thanks again for the correct info.


Still would like an answer from someone that knows for sure what this adjustment controls . 


Thank You


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## tadawson (Jan 3, 2018)

There are actually two adjustments in your photo. The top looks like idle speed, and assuming that the flange to the left is the engine side of the carb, that looks like idle mix, but in a relatively odd place. To know for sure, screw it in gently and count the number of turns until it bottoms, so that you can get it back where it is, and then see what effect it has on both idle and full throttle operation. 



I'm still betting on idle, since a downstream port behind the throttle plate is often used, since the main jet needs to feed fuel at the narrow portion of the venturi, which certainly isn't there. Then again, hard to tell what internal passages might be in that, but looks like the tip of the needle may well just regulate a port that goes directly into the carburetor bore. 



I feel like I've seem something like this once, but can't for the life of me recall on what . . .


Were you to provide the model mumber of the blower and serial number/year, that would help a lot. "621e" refers to a lot of Toro models, and it's not really possible to narrow it down based on just that. With the blower model, the main doc/parts list can be found, and Toro tends to list a lot of engine parts/info there as well . . .


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## JLawrence08648 (Jan 15, 2017)

Have you gone to Toro.com and looked at the owner's and service manual?


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## rjk8619 (Jan 29, 2019)

Thanks for all your help.

Yes, the upper adjustment is an idle adjuster.
The one I have inquired about is the lower one in the picture adjacent to the engine side mounting plate.

Based on Lawntoro comments, I have determined that the engine is Chinese either a loncin or a Lifan.
I have found a diagram of this carb in some lifan manual and they call this needle valve a " Mixture Adjustment Screw" 

I assume that it is an air mixture adjustment. And your are correct that the needle regulates a port that goes directly into the carburetor bore. see picture. I have removed the needle completely and cannot tell if there are any internal passages that connect to the needle bore. If this is in fact air mixture then turning in should rich the mixture and turning out should lean the mixture ? Right ?


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## rjk8619 (Jan 29, 2019)

I have gone to Toro.com and looked in both the owners and service manuals.
You kind of see the needle valve in question in the exploded view of the carb but it is not referenced either in the parts list or in the text.


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## JLawrence08648 (Jan 15, 2017)

rjk8619 said:


> The one I have inquired about is the lower one in the picture adjacent to the engine side mounting plate.
> 
> I have found a diagram of this carb in some lifan manual and they call this needle valve a " Mixture Adjustment Screw"
> 
> I assume that it is an air mixture adjustment. And your are correct that the needle regulates a port that goes directly into the carburetor bore. see picture. I have removed the needle completely and cannot tell if there are any internal passages that connect to the needle bore. If this is in fact air mixture then turning in should rich the mixture and turning out should lean the mixture ? Right ?


Low mixture, turning it in makes it lean, turning it out makes it richer. You generally want to start 1-1 1/2 turns out, then while running, turn it in until it runs a little crappy then turn it out 1/2 turn. You can also turn in until crappy then turn out until crappy and find the mid point, I do this first then follow my initial recommendation.


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## tadawson (Jan 3, 2018)

Concur. The air is coming down the carb throat past the throttle plate, held open for idle by the stop screw on top. Likely the needle is fed by nothing more than a passage coming from the float bowl directly to provide fuel at idle. As noted prior, typically the main jet is in the center of the venturi, and can be seen looking down the carb sticking up to about the center of the venturi. Depending on age, it's quite possible that the main needle is fixed, and the idle is adjustable . . . . odd, but not hard to grasp, since most emissions are output at power, not idle.


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## rjk8619 (Jan 29, 2019)

why do you think there seems to be no documentation on this adjustment ?

Thanks


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## JayzAuto1 (Jul 25, 2016)

That idle mixture screw must be for initial factory setup. I've gotten a few replacement carbs that have that screw intact, but the heads generally snap off once I tried to adjust them. But as others have said, that engine spends most of it's life at about 3600 RPM's, so that mixture screw has very little effect on performance. As far as documentation??? Most carbs will just have the stump remaining after the head snaps off. In this day and age of 'Dumbed Down" carbs, there is no need to adjust, nor does the EPA want you to adjust it.

GLuck, Jay


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## tadawson (Jan 3, 2018)

With some heat, I have never failed to get one of the "designed to break off" needles out intact, although most have been more the way Honda did it with a limiter cap on it. (Heat gets those as well . . . )


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## paulm12 (May 22, 2015)

Here is a similar carb that I replaced on a MTD machine (the carb was leaking gas into the crankcase). I don't know if this is OEM, or the PO had snapped off part of this needle/screw. There are threads, but there is no head on the screw/needle for adjusting. The replacement carb looked similar, ie, not user adjustable.


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## rjk8619 (Jan 29, 2019)

this one did have a plastic locking style of cap on it but it is easily removed and the needle valve is removed and installed easily.


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