# High Engine Speed - Air Vane Governor Question



## oldgeezer69 (Mar 21, 2017)

Toro Cr20E, Model# 38116, 2Stroke Tecumseh AH600.

Air vane Governor not pulling throttle plate closed, even after half hour running.
It is pulling somewhat on the throttle plate, as i see the spring moving, but not enough.
Spring + Plastic Air Vane Replaced, Rod Link is not obstructed.
For ease of carb adjustment, I am running unit with covers removed
Do I need the Red Plastic Shroud Covers in place to adjust the carb ?
Could Air Pressure build up at the vane be escaping, with covers removed??
Thus preventing the governor from closing throttle plate fully
Many many models of Toro had this Tecumseh airvane governor setup.
Therefore question is not "AH600" specific


B.T.W. Power screw & Idle screw are at default ONE turn out from Fully seated, which should be good enough, before any adjustments made while engine is under Load.
Thanks in Advance


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## JLawrence08648 (Jan 15, 2017)

Make sure there is freedom of movement in all the linkage, throttle, recheck if you need to; that the throttle linkage is in the correct holes; and the spring is attached to not only the correct hole on the throttle or air vane but also it's attached on the other end to the correct fixed point on the body. I


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## oldgeezer69 (Mar 21, 2017)

Thanks JLawrence08648 - - - All connections appear to be good.


$60,000 Question:: 
Can i adjust\tune carb with the all red plastic shroud covers removed?
Are the covers needed to be in place for proper Governor Operation?'

The covers are off because - - - - 
Engaging a flat blate screwdriver in the slotted power screw while engine is running is tricky, But would be far more difficult with covers in place.

You would probably need to StopEngine\Adjust\Restart-- ThrowSnow \StopEngine\Adjust\Restart-- ThrowSnow . . . .ETC
But that may be what i got to do, if the covers are needed to assist in "air build up" at that plastic governor vane


Many of these Toro Single stage units wth Tecumseh Ah520\Ah600,. . . Snowmaster20\S200\S620\Cr20\Cr20E were pretty similar in design,
So someone knows the answer to the above question
Thanks


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## JLawrence08648 (Jan 15, 2017)

Shroud covers are for safety, keep the engine warm, and for aesthetics. Go ahead and adjust away. Maybe you have a defective carb, needs PROPER cleaning. Maybe it's running too lean, or the oil mixture is too lean. This may be a problem for a good hands on mechanic to go one step at a time and run through things.


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## jtclays (Sep 24, 2010)

I don't think the blower covers are needed. The governor tab picks up the air behind the recoil shroud. There is no mention of the cosmetic covers in the manual. You can play around with engine speed by bending the tab the throttle spring mounts to on the carb stud nut. Is it screaming high speed or just running high rpm like it should? 
You can find the service manual here:
Go to mymowerparts.com, click on free parts and manuals in the red border, scroll down to tecumseh service-and-repair-manuals click it, next page the 2 cycle manual is the 8th link down. I can't get it to hyperlink into the post for some reason.


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## Grunt (Nov 11, 2013)

OR-

http://www.barrettsmallengine.com/manual/tecumseh2cyclemanual1994.pdf


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## oldgeezer69 (Mar 21, 2017)

Thanks JLawrenceo8648, jtclays, Grunt, for taking the time to respond.
Original post[Full post] was in “Toro” Forum from March 20th (still there), after getting no response I decided to try this forum.
The machine was my father-in-law's R.I.P.
I used it back in the early nineties. I call it the "attack dog", for the way it would take on snow Banks(excellent lightweight machine for a snow plow contractor-easily toss it in the back of a Truck moving from job tojob). When last used about 20 yrs ago it started and ran but would die underload. Finally i dug it out and rebuilt the carb.
When running afterthe carb rebuild it screamed like a Salem witch about to be burned.
The governor was making no attempt to close down thethrottle plate.
Dogging it in a snowbank I noticed every now and then the governor would actually kick in and do its spring Balancing Act.
On removing RecoilAssembly\BlowerHousing, I became aware of extreme sloppiness at the air van governor Pivot Point.
I further noticed that the lubricant on the plastic stem and in the locating hole appears to be NeverSeeze (love the stuff for spark plugs into aluminum cylinder heads, but it's not a lubricant, contains particulates, which can act similar to valve grinding paste).
To the naked eye the Locating hole appears to be slightly out of round, but i sure want to be WRONG on that. 
I replaced the spring and Plastic air vane and did see some improvement in governor operation. Throttle plate no longer wide open –But no where near being closed at its idle position. This got me thinking that perhaps without covers, i might be loosing air pressure at the vane.
Unfortunately the snow is all gone now so i cant test it under load, 
Just wondering: How the small engine shops load the motor when there is No snow around??
Anyway,the Final Chapter may not be written until next snow season
I apologize being new to forum’s, I don't know where the thanks buttons are but thank you all.


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## oldgeezer69 (Mar 21, 2017)

Thanks:: JLawrenceo8648, jtclays, Grunt, for taking the time to respond.
Original post[Full post] was in “Toro” Forum from March 20th (still there), after getting no response I decided to try this forum.
The machine was my father-in-law's R.I.P.
I used it back in the early nineties. I call it the "attack dog", for the way it would take on snow Banks(excellent lightweight machine for a snow plow contractor-easily toss it in the back of a Truck moving from job to job). When last used about 20 yrs ago it started and ran but would die under load. Finally i dug it out and rebuilt the carb.
When running afterthe carb rebuild it screamed like a Salem witch about to be burned.
The governor was making no attempt to close down the throttle plate.
Dogging it in a snowbank I noticed every now and then the governor would actually kick in and do its spring Balancing Act.
On removing RecoilAssembly\BlowerHousing, I became aware of extreme sloppiness at the air van governor Pivot Point.
I further noticed that the lubricant on the plastic stem and in the locating hole appears to be NeverSeeze (love the stuff for spark plugs into aluminum cylinder heads, but it's not a lubricant, contains particulates, which can act similar to valve grinding paste).
To the naked eye the Locating hole appears to be slightly out of round, but i sure want to be WRONG on that. 
I replaced the spring and Plastic air vane and did see some improvement in governor operation. Throttle plate no longer wide open –But no where near being closed at its idle position. This got me thinking that perhaps without covers, i might be loosing air pressure at the vane.
Unfortunately the snow is all gone now so i cant test it under load, 
Just wondering: How the small engine shops load the motor when there is No snow around??
Anyway,the Final Chapter may not be written until next snow season
I apologize being new to forum’s, I don't know where the "THANKS" buttons are, but thank you all.


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## Grunt (Nov 11, 2013)

Thank you for posting what you have done and the current status of the problem. Below is a link to the Toro single stage repair manual for future reference. The manual states your max engine RPM's as 4300-4700. Your engine is not designed to idle down and the governor's job is to maintain the max RPM's "under a load".

http://gicl.cs.drexel.edu/images/0/02/Service_manual.pdf


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## Angeou (Sep 6, 2019)

The function of the governor is to automatically adjust the fuel supply quantity in accordance with the change of the external load of the diesel engine within the working speed range of the diesel engine to keep the diesel engine speed basically stable. For diesel engines, changing the fuel supply requires only turning the plunger of the fuel injection pump. As the oil supply increases, the power and torque of the diesel engine increase accordingly, and vice versa.

According to the different working principle of the governor, it can be divided into mechanical governor, electronic governor and electronic injection governor.


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## ST1100A (Feb 7, 2015)

Most of those little two stroke engines were not designed to idle, they usually had a fixed throttle set to high idle working speed. The carbs were not designed to idle too well either, they were designed for maximum governed engine speed. They would not carburate well at idle speed, meaning they wont mix fuel with air properly.
I did see a problem already with the little screw that attaches the butterfly valve/throttle plate to the throttle shaft falling out and getting sucked into the engine while it was running. When that happens you won't be able to get the engine to slow down enough to an idle speed, even when you take your hand and physically turn the throttle shaft down to an idle, the engine will keep racing because of the air leak through the hole where the throttle plate screw was. Another thing that can happen is when the throttle plate moves out of position in the shaft and becomes jammed causing the throttle to stick in the open position.
Also make sure your carb is tight to the mounting surface and the gasket is not leaking, and a worn throttle shaft or bushing can also cause an air leak and a high idle speed. That is common on those older two stroke engines.
Another thing that can cause two strokes to not idle well is worn crankshaft seals and crankcase vacuum leaks, either from any seals or gaskets, to porosity in the aluminum cases, which was very common in those little motors when they got older.


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