# Toro S-620 Snow Thrower



## RKDOC (Jun 20, 2006)

I am working on the Toro S-620 1985 snow thrower. I cleaned the carburetor and have it started and running. On the side of the carb are two adjusting screws. I figured on was high speed and the other low speed. However the blower only runs at full throttle, there is no speed control. What then do the adjusting screws do? and how are they to be adjusted? The IPL say's that one is the Idle Adjusting screw the other is the main adjusting screw. The engine is a Tecumseh (sorry I don't have the model number right now) two stroke engine. Any advise will be greatly appreciated. Have a happy holiday's.


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## RKDOC (Jun 20, 2006)

I got some numbers off the engine and snow thrower. The engine numbers are 1622M 6246 i don't think these are Tecumseh numbers, the engine is probably a Toro built engine. The numbers off the blower are Model 38165 serial 7016249. The carb has the primer line going into the bottom of the cab with a manual choke on it. One fuel line with no return line. I need to know how to adjust the carb. 

Thanks in advance for any help.


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## Airman (Jan 7, 2009)

Most Toro snow blower engines are Tecumseh. I will assume yours is. This manual may help.
http://www.cpdonline.com/692508.pdf


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## 30yearTech (Sep 14, 2006)

The 1985 Toro S-620 Snow blower shows to be a Toro Model number 38162 and was equipped with a Tecumseh 2 - Cycle engine model AH600-1623

The two screws on the side near the bottom of the carburetor are the Low and High speed adjustment screws, if it's a constant speed throttle design, then the only adjustment you will need to fine tune is the high speed setting. You should be alright with the initial setting on the low speed adjustment.


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## pyro_maniac69 (Aug 12, 2007)

all the low speed adjustment is for is for when you put the motor under a load, if you hit some snow and it dies, you need to richen the low speed just a hair


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## RKDOC (Jun 20, 2006)

Thankis for all the help. i adjusted the screws as you directed and the blower works great.

Thanks


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## 30yearTech (Sep 14, 2006)

pyro_maniac69 said:


> all the low speed adjustment is for is for when you put the motor under a load, if you hit some snow and it dies, you need to richen the low speed just a hair


I really wonder about you some times pyro, the load adjustment screw is the High speed adjustment. The low speed is adjusted for smooth throttle from Idle, a fixed speed engine is usually set to run at top speed all the time.


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## pyro_maniac69 (Aug 12, 2007)

right but, when these little engine try pushing some heavier snow, and you don't have the low just right, they will bog and die, thats how I adjust them for customers when there is snow on the ground, I put them back together, get the high speed adjustment set to where it will run at top no load speed smoothly, than I put it under a load, there have been many times that as soon as I hit the snow they will die, after I adjust the low end slightly, they will just dig through the snow and won't stop at times


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## RKDOC (Jun 20, 2006)

My friend (who is a Toro Dealer) got me a service manual off of the toro web site. it say's set the idle adjustment screw at 7/8 turn open. Then set power adjustment screw to 5/8 open. If blower stalls when going into snow, open the power screw 1/8 turn until blower does not stall when blowing snow.


I got the service manual after I got the blower running following everyone's help. Thanks a bunch.


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## 30yearTech (Sep 14, 2006)

RKDOC said:


> My friend (who is a Toro Dealer) got me a service manual off of the toro web site. it say's set the idle adjustment screw at 7/8 turn open. Then set power adjustment screw to 5/8 open. If blower stalls when going into snow, open the power screw 1/8 turn until blower does not stall when blowing snow.
> 
> 
> I got the service manual after I got the blower running following everyone's help. Thanks a bunch.


That's right. If you have the governor set correctly, and the engine is running at top speed, the low speed adjustment is not the one you should adjust if the engine stalls under a load. When the engine is running at a high speed the majority of fuel is metered through the main jet. Some fuel does make it's way through the low speed circuit, so adjusting it may help, but the adjustment should really be made to the high/load adjustment. :thumbsup:


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## Ned120 (Nov 14, 2009)

Reference to the Tacumseh manual I used to get my older model running:

http://www.smallenginesuppliers.com...umseh_2-Cycle_Engines_Service_Information.pdf


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## Maytag (Dec 10, 2007)

Sorry for the late post, but I have to chime in. 
Why would you want a machine (snow blower, chain saw, etc.) to run smoothly at no load? The instant you apply a load it's more apt to run poorly. Instead, adjust it to "just" run rough (forgive me I don't recall which side of smoothly - rich side I'm think'n) so that the instant you apply a load it is forced "back" to smoothly.
I tried adjusting my own chain saw years ago for smoothly when wide open and it ran bad as soon as the chain hit the log. Took it in to have it adjusted and the tech showed me the difference. Set it for rough and WOOOWWW when it hits the log. You couldn't kill it. It went throught the log like butter and never coughed once. It "got down to business" !
Hope this post makes sense. 

>Maytag


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## 30yearTech (Sep 14, 2006)

Maytag said:


> Sorry for the late post, but I have to chime in.
> Why would you want a machine (snow blower, chain saw, etc.) to run smoothly at no load? The instant you apply a load it's more apt to run poorly. Instead, adjust it to "just" run rough (forgive me I don't recall which side of smoothly - rich side I'm think'n) so that the instant you apply a load it is forced "back" to smoothly.
> I tried adjusting my own chain saw years ago for smoothly when wide open and it ran bad as soon as the chain hit the log. Took it in to have it adjusted and the tech showed me the difference. Set it for rough and WOOOWWW when it hits the log. You couldn't kill it. It went throught the log like butter and never coughed once. It "got down to business" !
> Hope this post makes sense.
> ...


You may want to go back and read the posts again. No one stated to adjust the carburetor to run smoothly at no load. 

Adjustments procedures for a governed engine are going vary slightly from a non governed engine (i.e. chainsaw). A governed engine running with no load will seem to run more smoothly with only a partial throttle opening. When a load is applied and the throttle opens, then more fuel is fed out through the main jet, and with a continued load the engine will still seem to run smooth.

If you were to override the governor and hold the throttle open, then you should get the four cycling sound you are looking for with a properly adjusted carburetor. This type of engine is not meant to run at these higher RPM's and can cause serious engine damage, so it's not recommended to adjust this engine using the same methods for chains saw's or non governed engines that are designed to run at much higher RPM's. Instead this type of engine is adjusted for smooth throttle response from no load to load.


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## rramer886 (2 mo ago)

pyro_maniac69 said:


> right but, when these little engine try pushing some heavier snow, and you don't have the low just right, they will bog and die, thats how I adjust them for customers when there is snow on the ground, I put them back together, get the high speed adjustment set to where it will run at top no load speed smoothly, than I put it under a load, there have been many times that as soon as I hit the snow they will die, after I adjust the low end slightly, they will just dig through the snow and won't stop at times


 WHICH SCREW IS WHICH?


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## Milton Fox Racing (May 27, 2014)

Ned120 said:


> Reference to the Tacumseh manual I used to get my older model running:
> 
> http://www.smallenginesuppliers.com...umseh_2-Cycle_Engines_Service_Information.pdf


Look on page 15 of the above link and follow the guidance as outlined there....


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## paulr44 (Oct 14, 2008)

On any 2-stroke, the screw closest to the manifold is the low-speed, the closest to the intake/air filter is the high speed.


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