# Low Idle speed for Tecumseh HS50



## Toro-8-2-4 (Dec 28, 2013)

Can anyone provide the low Idle speed on a Toro 521 with a Tecumseh HS50? I know on most Briggs engines it is about 1750RPM

I am trying to set the low idle and the engine will not stay running in about 2400-2500RPM range. In the 2500-2600RPM range it will idle and stay running.

I have used both the original carb after cleaning and a new aftermarket carb. new intake gaskets. New spark plug. Inspected the head gasket. I have adjusted the governor and installed new fuel line. It will idle for a minute or two and then die. At about 2500-2600 RPM it will idle and keep running.

I don't know what the published low idle speed is. I have looked and can not find it in any Tecumseh info that I have found.. It may be that it is not designed to idle slower. 

It seems to run fine on the high speed but I dont have any snow to load test it.

Any ideas? thanks.


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## ST1100A (Feb 7, 2015)

You probably have a clog in the low speed/idle jet hole. Another thing could be your valve clearance is too tight and that will cause idle problems, usually it wont idle, and more so when the engine gets warmed up and hot.


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## 140278 (Aug 27, 2020)

i agree with st1100a
recheck for a plug in the idle circuit ,check to make sure the idle mixture screw on the side of the carb is adjusted correctly, if it has one or the circuit is plug'd you will not idle below 2500 rpm as that's where the high speed circuit takes over.,


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## Ziggy65 (Jan 18, 2020)

Low idle speed on the Tecumseh engines is 1750 -1800 RPM


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## Toro-8-2-4 (Dec 28, 2013)

ST1100A said:


> You probably have a clog in the low speed/idle jet hole. Another thing could be your valve clearance is too tight and that will cause idle problems, usually it wont idle, and more so when the engine gets warmed up and hot.


Perhaps the idle circuit is not fully clear. However, a brand new carb has done the same. Granted it is an aftermarket knock off. The restrictor pin in the idle circuit is freely moving. I can hear it when I shake the carb and it can be seen when the idle jet is removed. The valve lashes are right in the middle of the spec. I did remove the head and clean the carbon and visually inspect the valves. There is slight play in the guides. I have seem much worse on good running engines. Again, the clearances are in spec.




captchas said:


> i agree with st1100a
> recheck for a plug in the idle circuit ,check to make sure the idle mixture screw on the side of the carb is adjusted correctly, if it has one or the circuit is plug'd you will not idle below 2500 rpm as that's where the high speed circuit takes over.,


I will reclean the original carb and reinstall it. As you all know the idle circuit is blind and the only way to really know how clean it may be is to remove the ball plugs and then epoxy the holes back up.




Ziggy65 said:


> Low idle speed on the Tecumseh engines is 1750 -1800 RPM


Thank you.


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## paulm12 (May 22, 2015)

per the Toro 521 specs (1988 model) 

*Engine:* Engine Speed
High 3300, Low 2200±150 RPM 

I always thought the low speed was a bit high, but I checked for several years of that model, and that is what is called out.

tx


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## classiccat (Mar 1, 2014)

What year is your engine...or do you know if it has points or electronic ignition? if it's points and someone got in there that didn't know what they were doing, gap &/or spark advance could be out to lunch.


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## Toro-8-2-4 (Dec 28, 2013)

paulm12 said:


> per the Toro 521 specs (1988 model)
> 
> *Engine:* Engine Speed
> High 3300, Low 2200±150 RPM
> ...


I was reading something saying the oil pump does not lubricate well at the low idle speeds so that sounds believable.
My tach broke yesterday. just dropped it about 12" on to pavement and it stopped working..... so frustrating. Thanks for the info.




classiccat said:


> What year is your engine...or do you know if it has points or electronic ignition? if it's points and someone got in there that didn't know what they were doing, gap &/or spark advance could be out to lunch.


Excellent comment but it is electronic ignition.Thanks


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## 3vanman (Nov 21, 2017)

Toro-8-2-4 said:


> I was reading something saying the oil pump does not lubricate well at the low idle speeds so that sounds believable.
> 
> I may be confused (I regularly am) but is not an HS50 a "splash" lubricated engine? Do they have an oil pump? I know some of the small Tecumseh engines do, but did not think the HS50 did.


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## Oneacer (Jan 3, 2011)

Its a splash lube engine, as I am not aware of any "oil pump".


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## Toro-8-2-4 (Dec 28, 2013)

OK thanks. What I read may have been in reference to a different Tecumseh engine. I have been scaning a lot of material in the past week and it becomes easy to conflate info.


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