# My forever increasing RPM John Deere 724D Tecumseh



## greencuda68 (Jan 19, 2021)

Greetings All,

New to the Forum but I'm surely looking forward to communicating with the forever learning graduates of the School of Hard Knocks. LOL. I recently picked up a dump bound snowblower that sat for several years. It was given to a buddy of mine who who replaced the carburetor and priming bulb with a Chinese knockoff carburetor. The problem he had was uncontrollable increasing RPM's. When I got the blower, I cleaned the old tecumseh 640058 carburetor (non-adjustable), verified all the pieces, parts and orifices were clear and checked that the needle valve and float seated properly and then reinstalled the cleaned original non adjustable 640058. Low and behold I'm having the same issue. I have an el cheapo rpm indicator from amazon and the rpm's are indicating 4400 rpm with the throttle plate fully closed. This completely baffled me since I don't understand how the engine could run at such an excessive rpm with the throttle plate fully shut. My buddy did adjust the governor and I also checked that this was set correctly by watching youtube videos. With throttle fully open, loosen governor arm lock bolt and rotate governor shaft fully counterclockwise and then tighten locking bolt.

Here's other information or something I have tried:
1.) the governor linkage seems loose but I'm unfamiliar with how it should feel
2.) the low speed idle screw is completely backed out with engine at 4400 rpm ??
3.) if i open the throttle up a little, engine will run away and most likely blow up. lots of room with respect to more available rpm
4.) engine will not start with chock at all. I need to use starting fluid but engine runs fine after starting fluid start, no smoke and sounds great but high rpm's
5.) i'm using 91 octane non-ethanol fuel
6.) with engine running, i have sprayed carb cleaner around both engine to intake and intake to carb flanges looking for a decrease in rpm. result-->no decrease
7.) engine does drop about 300 rpm with auger engaged

I have also thought about replacing carburetor with something I can adjust but not sure which one I will need?

Other info: model OHSK70-72516C 
Engine Family YTPXS.1951AF
John Deere carburetor p/n AM127583

So that's it , small engine enthusiasts , I'm open for any recommendations anyone may have. I thank you all in advance for your time. I'm determined to figure this out. 


Joe


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## Kiss4aFrog (Nov 3, 2013)

Welcome to SBF Joe









I think I see a line for a primer bulb. Does the machine have one ? If you push it four or five times do you get some gas coming out of the carbs throat ?
What are you using to measure RPM ?


.


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## crazzywolfie (Jun 2, 2014)

welcome. 

are you sure the spring from the governor arm to the throttle is in the right hole? it looks like there is a lot of slack in it


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## greencuda68 (Jan 19, 2021)

Kiss4aFrog said:


> Welcome to SBF Joe
> View attachment 174064
> 
> 
> ...


Why Hello and Quick Reply 

I just went into the garage and the primer bulb is operating correctly. Gas came out the carb throat while priming. In fact, I was able to to start the blower without ether. (but i had engine running an hour or two ago). I accidentally had the gas shutoff turned off and it engine was running better. When I opened the fuel shutoff with the engine on, the rpm's increased from about 3600 to 3950 in about two and one-half minutes and was still climbing. I'm beginning to wonder if the float valve seat is leaking by slightly and the carburetor is dumping excess fuel into the intake?? The RPM meter was checked on another blower and was steady at 3600 rpm. You can also hear the increase in engine speed as the unit speeds up on its own.


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## Ziggy65 (Jan 18, 2020)

Welcome Greencuda68, great car by the way  Any photos? We love photos.

That John Deere was built by Ariens, and appears to be in very good condition, well worth keeping and repairing.

If you are actually running 4400 rpm, it could be a linkage is not connected correctly, such as crazzywolfie suggests.

Tecumseh carb manual and Quick reference service manual, which has some info on governor and carb set up:


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## Kiss4aFrog (Nov 3, 2013)

Edited: Video below shot my guess on the linkage out of the water, sorry.
Ziggy, I was thinking the same thing on the tach except he said he tried it out on another machine so it's accurate 😕
.


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## paulm12 (May 22, 2015)

does this help: 



 I cant see the top of your carb.

and yes, Crazzy, evidently that strange setup appears correct.


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## greencuda68 (Jan 19, 2021)

crazzywolfie said:


> welcome.
> 
> are you sure the spring from the governor arm to the throttle is in the right hole? it looks like there is a lot of slack in it


Thanks....
I'm not sure, but some pictures I've found online suggests it is ? The real question is regardless of the governor, the engine increases RPM's with the throttle plate fully in the low speed position (fully closed). The governor is effectively out of service in this throttle position and is not controlling anything. My understanding of the governor is that it will mechanically open the throttle plate when rpm's drop to bring engine speed back up? I've have also had someone else tell me the governor may be the issue but I can't wrap my head around the fact that the engine is in an idle position with respect to the throttle and RPM's are increasing on there own with no load on engine.


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## Kiss4aFrog (Nov 3, 2013)

In that video the spring is in hole #4


.


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## greencuda68 (Jan 19, 2021)

paulm12 said:


> does this help:
> 
> 
> 
> ...


That's exactly the setup. Wow


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## Rooskie (Feb 12, 2015)

greencuda68 said:


> Greetings All,
> 
> New to the Forum but I'm surely looking forward to communicating with the forever learning graduates of the School of Hard Knocks. LOL. I recently picked up a dump bound snowblower that sat for several years. It was given to a buddy of mine who who replaced the carburetor and priming bulb with a Chinese knockoff carburetor. The problem he had was uncontrollable increasing RPM's. When I got the blower, I cleaned the old tecumseh 640058 carburetor (non-adjustable), verified all the pieces, parts and orifices were clear and checked that the needle valve and float seated properly and then reinstalled the cleaned original non adjustable 640058. Low and behold I'm having the same issue. I have an el cheapo rpm indicator from amazon and the rpm's are indicating 4400 rpm with the throttle plate fully closed. This completely baffled me since I don't understand how the engine could run at such an excessive rpm with the throttle plate fully shut. My buddy did adjust the governor and I also checked that this was set correctly by watching youtube videos. With throttle fully open, loosen governor arm lock bolt and rotate governor shaft fully counterclockwise and then tighten locking bolt.
> 
> ...


Welcome to the snowblower forum!
Does this thread help?








Tecumseh 8 HP Over Reving all of Sudden


Hello All Tecumseh HMSK80 155487S The Guy across the Street was snow blowing my driveway for me while I was away on a trip. All of a Sudden the engine started to Over Rev. No warning did not touch anything just happen. I can work on Small Engines so tried over the phone to help him - He...




www.snowblowerforum.com


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## greencuda68 (Jan 19, 2021)

Ziggy65 said:


> Welcome Greencuda68, great car by the way  Any photos? We love photos.
> 
> That John Deere was built by Ariens, and appears to be in very good condition, well worth keeping and repairing.
> 
> ...


Thanks for these documents. I'll check them out a little later.


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## greencuda68 (Jan 19, 2021)

greencuda68 said:


> Thanks for these documents. I'll check them out a little later.


The green barracuda was my first car. 150 dollars and a convertible. Wish I still had her................


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## crazzywolfie (Jun 2, 2014)

if it is reving up with the throttle in the closed position that would usually mean there is a vacuum leak because it is sucking air in from somewhere else to burn the fuel it is getting.


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## greencuda68 (Jan 19, 2021)

crazzywolfie said:


> welcome.
> 
> are you sure the spring from the governor arm to the throttle is in the right hole? it looks like there is a lot of slack in it





paulm12 said:


> does this help:
> 
> 
> 
> ...


Here are a couple more photos. With throttle low, upper spring disengaged, With throttle high, lower spring disengaged


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## greencuda68 (Jan 19, 2021)

Kiss4aFrog said:


> In that video the spring is in hole #4
> 
> 
> .


Thanks for that detail. I'm game to try anything


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## greencuda68 (Jan 19, 2021)

crazzywolfie said:


> if it is reving up with the throttle in the closed position that would usually mean there is a vacuum leak because it is sucking air in from somewhere else to burn the fuel it is getting.


I checked the gasket from the engine to the intake and the intake to the carburetor. Can you think of anywhere else to check for a vacuum leak ? I'm also wondering if a leaky needle and float seat could raise engine rpm's or would this simply flood the engine ?


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## crazzywolfie (Jun 2, 2014)

if the needle/seat was leaking it would cause the machine to run rich till it stalls out. in that video the governor spring was 1 hole lower. i don't know if that will make any difference or not but might be worth trying


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## greencuda68 (Jan 19, 2021)

crazzywolfie said:


> if the needle/seat was leaking it would cause the machine to run rich till it stalls out. in that video the governor spring was 1 hole lower. i don't know if that will make any difference or not but might be worth trying


I'll give it a try. Thanks !


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## nwcove (Mar 2, 2015)

Can you visually see that the throttle plate is closed or are you assuming it is because you have the controls in the idle position?


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## greencuda68 (Jan 19, 2021)

nwcove said:


> Can you visually see that the throttle plate is closed or are you assuming it is because you have the controls in the idle position?


I can physically see that the throttle plate is fully closed. The low idle screw is all the way out. The low idle rest tab on the throttle plate is completely spring shut by the throttle return spring.
Thanks for the question


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## AandPDan (Nov 18, 2014)

If the throttle plate is physically closed then it is NOT a governor problem.
You have to be getting air/fuel past the throttle, somehow.


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## nwcove (Mar 2, 2015)

AandPDan said:


> If the throttle plate is physically closed then it is NOT a governor problem.
> You have to be getting air/fuel past the throttle, somehow.


it has to be getting a bunch of air somewhere behind the throttle plate if the plate is staying closed.


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## greencuda68 (Jan 19, 2021)

AandPDan said:


> If the throttle plate is physically closed then it is NOT a governor problem.
> You have to be getting air/fuel past the throttle, somehow.


OK Thanks. Even though both intake gaskets appear ok, that may be a good place to start. I also noticed the small spring on the carburetor float is missing. I'm getting mixed messages whether or not that spring is required ?


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## Oneacer (Jan 3, 2011)

If it wasn't needed, they would not use it ....


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## greencuda68 (Jan 19, 2021)

oneacer said:


> If it wasn't needed, they would not use it ....


Good Point ! I sure hope that little spring is the problem. Now, it may just be an issue to locate a replacement spring. It's listed on the 640058 carburetor exploded view but, when you go to the parts list its not available? I've tried several websites.


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## AandPDan (Nov 18, 2014)

The spring serves to "dampen" the float.
It's part # 632386 and is available, even from Ebay.


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## Preacherman (Dec 20, 2020)

greencuda68 said:


> OK Thanks. Even though both intake gaskets appear ok, that may be a good place to start. I also noticed the small spring on the carburetor float is missing. I'm getting mixed messages whether or not that spring is required ?


That spring must only be used on certain models as this pic doesn’t show the spring. I can’t see it causing your issue but I have had stranger problems with equipment.


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## ST1100A (Feb 7, 2015)

If your governor linkage is adjusted properly you may want to check to see if one of the tiny screws that holds the butterfly valve in place in the carburetor has not come loose and fell out and got sucked into the engine. That will cause the high speed running problem like you have an air leak somewhere, which you would have from the air leaking past the throttle plate.
That was a very common problem on John Deere snow blower engines.
I can see from the picture the screw is in the choke plate, check the throttle plate that is next to the intake manifold.
Another thing, the spring linkage does not look right with the piece attached to the spring causing extra tension on it so it wont let the throttle slow itself down enough.
That might not be the correct throttle spring in the first place and the way they have it hooked up, it looks like it is set up to be a 'Fixed Throttle' so your control lever will not function properly.


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## greencuda68 (Jan 19, 2021)

ST1100A said:


> If your governor linkage is adjusted properly you may want to check to see if one of the tiny screws that holds the butterfly valve in place in the carburetor has not come loose and fell out and got sucked into the engine. That will cause the high speed running problem like you have an air leak somewhere, which you would have from the air leaking past the throttle plate.
> That was a very common problem on John Deere snow blower engines.
> I can see from the picture the screw is in the choke plate, check the throttle plate that is next to the intake manifold.
> Another thing, the spring linkage does not look right with the piece attached to the spring causing extra tension on it so it wont let the throttle slow itself down enough.
> That might not be the correct throttle spring in the first place and the way they have it hooked up, it looks like it is set up to be a 'Fixed Throttle' so your control lever will not function properly.


Thanks for that advice on that throttle plate screw. Now, that's thinking outside the box. I'll check that out. Also, do you know what physically holds the throttle plate shaft in place. I was able to raise the shaft a little bit which allowed the low speed idle tab on throttle plate to increase its clockwise rotation a little bit. This helped decrease the RPM's slightly. The governor linkage is relaxed with the throttle plate fully clockwise (shut position) and high RPM's still exist. Thanks again for your input !


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## greencuda68 (Jan 19, 2021)

AandPDan said:


> The spring serves to "dampen" the float.
> It's part # 632386 and is available, even from Ebay.


I went to the John Deere website and the spring is not shown. Very interesting. Thanks for the part number !


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## Oneacer (Jan 3, 2011)

Its part #31 in that pic.


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## Preacherman (Dec 20, 2020)

oneacer said:


> Its part #31 in that pic.


he is not referring to the “clip”. On another diagram there is a spring. #26 I think it is model specific.


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## greencuda68 (Jan 19, 2021)

Yes, the float spring. Thanks for this diagram.


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## ST1100A (Feb 7, 2015)

#26 spring is to help keep the float from bouncing too much.
The throttle plate/butterfly valve is what holds the throttle shaft in place.


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## crazzywolfie (Jun 2, 2014)

but didn't it show the exact same symptoms even with the brand new carb that you removed? i would assume if it does the same thing with 2 different carb the issue might not be in the carb which doesn't leave a whole lot else. does leaving the choke closed effect it any?


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## greencuda68 (Jan 19, 2021)

crazzywolfie said:


> but didn't it show the exact same symptoms even with the brand new carb that you removed? i would assume if it does the same thing with 2 different carb the issue might not be in the carb which doesn't leave a whole lot else. does leaving the choke closed effect it any?
> [/QU





ST1100A said:


> If your governor linkage is adjusted properly you may want to check to see if one of the tiny screws that holds the butterfly valve in place in the carburetor has not come loose and fell out and got sucked into the engine. That will cause the high speed running problem like you have an air leak somewhere, which you would have from the air leaking past the throttle plate.
> That was a very common problem on John Deere snow blower engines.
> I can see from the picture the screw is in the choke plate, check the throttle plate that is next to the intake manifold.
> Another thing, the spring linkage does not look right with the piece attached to the spring causing extra tension on it so it wont let the throttle slow itself down enough.
> That might not be the correct throttle spring in the first place and the way they have it hooked up, it looks like it is set up to be a 'Fixed Throttle' so your control lever will not function properly.


*So this is how the story Ends*  ...................

*Thanks to All Participating Forum members*................ for all the input and Brainstorming of my Apollo 13 mission (_*A.K.A John Deere 724D)*_ ! Today, I went out and pulled the old carburetor off to check the tightness of the throttle plate screw. Guess What? The screw was ever so slightly loose and even though the plate appeared shut to this rookie, it wasn't. It was ever so slightly open. I verified this by looking at the new Chinese carburetor which had the throttle plate completely shut. With the screw slightly loose, the rotation of the throttle plate shaft was slightly reduced. Also, the throttle plate low idle adjust tab was hitting the body of the carburetor and also contributed to the throttle plate not fully shutting. So, I bent this tab a little bit to allow the throttle plate to fully shut......So help me God ! I also, considered the brainstorming input of a vacuum leak and I began to think about why both carburetors had runaway rpm's. The old carburetor gasket was used on both carburetors. I examined the gasket a little closer and found that it looked suspicious. I fabricated a new gasket and used a file to ever so gently draw file the manifolds flange on the intake manifold to verify its flatness. I tightened up the old carburetor with the new gasket and started up the unit ! I now have control of the engine while the engine is idling and the range of travel to full RPM appears OK. I still have the ability to over speed the engine with the throttle but I can manufacture a stop on the throttle control. I also played with the governor and ended up using hole #4. There seemed to be a little better engine control with this setting. So, I technically performed 4 actions to correct the rpm problem. As I like to call "Shotgun Maintenance"
1.) tightened hold down screw on throttle plate
2.) bent the low idle tab on throttle control linkage to allow better range of shaft motion to allow the use of low speed idle screw and fully close the throttle plate
3.) fabricated a new carburetor to intake manifold gasket
4.) Shifted governor spring to hole #4
















I have attached a couple of pictures. Old carburetor gasket, throttle control low speed idle tab hitting carburetor body


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## crazzywolfie (Jun 2, 2014)

that is good to hear. i was running out of idea's. you could try hole 5 on the governor arm. i believe the different holes are to speed up or slow down the engine at full throttle depending on your needs.


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## greencuda68 (Jan 19, 2021)

crazzywolfie said:


> that is good to hear. i was running out of idea's. you could try hole 5 on the governor arm. i believe the different holes are to speed up or slow down the engine at full throttle depending on your needs.


Thanks Again for your Help


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## toromike (Aug 20, 2018)

greencuda68 said:


> *So this is how the story Ends*  ...................
> I still have the ability to over speed the engine with the throttle but I can manufacture a stop on the throttle control.
> . . .


Maybe it's not over. The tab that hangs down from the throttle control (that connects to the spring going to the governor) controls the maximum speed at full throttle, bend the tab to set the desired maximum full throttle speed. Also, this engine appears to have a governed idle speed, bend the other non-moving tab to set the governed idle speed.


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## greencuda68 (Jan 19, 2021)

toromike said:


> Maybe it's not over. The tab that hangs down from the throttle control (that connects to the spring going to the governor) controls the maximum speed at full throttle, bend the tab to set the desired maximum full throttle speed. Also, this engine appears to have a governed idle speed, bend the other non-moving tab to set the governed idle speed.


Mike, I would most definitely like to be able to set these parameters. I attached a picture. Do I have the right tabs identified? This ending keeps getting better. My little brain is absorbing knowledge big time. lol. Thanks Again !!
Thanks Again..


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## toromike (Aug 20, 2018)

The tab that moves with the throttle lever sets the maximum full throttle speed (tab on left). Move the throttle lever to full and bend the tab to adjust to the desired speed. The tab on the right (labeled "high gov tab") looks like it should set a governed idle speed. Move the throttle to the idle position, make sure the throttle stop screw on the carb is set for a speed below the desired idle speed, then adjust the tab for the desired idle speed. You can always just use the carb idle stop screw to set the speed if you want, just bend the tab so it is not pulling on the spring.


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## crazzywolfie (Jun 2, 2014)

i would still recommend using the holes in the governor arm first. i believe that is why they are there. then if you can't get it to where you want then start bending the tab.


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## greencuda68 (Jan 19, 2021)

toromike said:


> The tab that moves with the throttle lever sets the maximum full throttle speed (tab on left). Move the throttle lever to full and bend the tab to adjust to the desired speed. The tab on the right (labeled "high gov tab") looks like it should set a governed idle speed. Move the throttle to the idle position, make sure the throttle stop screw on the carb is set for a speed below the desired idle speed, then adjust the tab for the desired idle speed. You can always just use the carb idle stop screw to set the speed if you want, just bend the tab so it is not pulling on the spring.


Thanks.........The ending is near


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## greencuda68 (Jan 19, 2021)

crazzywolfie said:


> i would still recommend using the holes in the governor arm first. i believe that is why they are there. then if you can't get it to where you want then start bending the tab.


Thank You for the advice Crazzywolfie !


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## Rooskie (Feb 12, 2015)

greencuda68 said:


> *So this is how the story Ends*  ...................
> 
> *Thanks to All Participating Forum members*................ for all the input and Brainstorming of my Apollo 13 mission (_*A.K.A John Deere 724D)*_ ! Today, I went out and pulled the old carburetor off to check the tightness of the throttle plate screw. Guess What? The screw was ever so slightly loose and even though the plate appeared shut to this rookie, it wasn't. It was ever so slightly open. I verified this by looking at the new Chinese carburetor which had the throttle plate completely shut. With the screw slightly loose, the rotation of the throttle plate shaft was slightly reduced. Also, the throttle plate low idle adjust tab was hitting the body of the carburetor and also contributed to the throttle plate not fully shutting. So, I bent this tab a little bit to allow the throttle plate to fully shut......So help me God ! I also, considered the brainstorming input of a vacuum leak and I began to think about why both carburetors had runaway rpm's. The old carburetor gasket was used on both carburetors. I examined the gasket a little closer and found that it looked suspicious. I fabricated a new gasket and used a file to ever so gently draw file the manifolds flange on the intake manifold to verify its flatness. I tightened up the old carburetor with the new gasket and started up the unit ! I now have control of the engine while the engine is idling and the range of travel to full RPM appears OK. I still have the ability to over speed the engine with the throttle but I can manufacture a stop on the throttle control. I also played with the governor and ended up using hole #4. There seemed to be a little better engine control with this setting. So, I technically performed 4 actions to correct the rpm problem. As I like to call "Shotgun Maintenance"
> 1.) tightened hold down screw on throttle plate
> ...


A Happy Ending!
Thank You for posting the solution.


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## greencuda68 (Jan 19, 2021)

Rooskie said:


> A Happy Ending!
> Thank You for posting the solution.


I'm very Thankful for the Forum's knowledge base and the members gift of time to help a fellow learning enthusiast. Brainstorming and communicating a solution was a lot of fun. Maybe this thread will help others learn how to fish in the sea of "Small Engine Repair"


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