Carb adjustment or?

[Heatingman 971]

So been driving the B80 around a little. Its got the 8 HP kohler motor k181s 
 

Maybe its normal, but the engine pitch and speed seems to change a bit when going over the small hills in the yard. 
 

And if I have the motor speed is at low throttle, at times the motor will die out when going into gear (when the load is applied to the motor at clutch release)

 

Normal or carb issue?

 

 

[Wheelhorse#1 1,829]

Sound like it made need a float adjustment, possibly sticking or the high speed screw on the carb needs to be adjusted.

 On high speed screw its 2 turns counter clockwise from all the way closed. Ajust it at full throttle under load but let it warm up first.Ill post a link if I can find it.

Edited October 9, 2022 by Wheelhorse#1

[ebinmaine 72,530]

2 hours ago, Heatingman said:

Maybe its normal, but the engine pitch and speed seems to change a bit when going over the small hills in the yard.

Governor adjustment been properly done?

 

[Heatingman 971]

1 hour ago, ebinmaine said:

Governor adjustment been properly done?

 

I believe so. Took some fiddling a while back. But got it to max just under 3600 rpm at full throttle.

 

[ebinmaine 72,530]

17 minutes ago, Heatingman said:

I believe so. Took some fiddling a while back. But got it to max just under 3600 rpm at full throttle.

 

Ahh but that's not the governor. 

That's max RPM.  

Not sure how to set that... 

[Heatingman 971]

5 minutes ago, ebinmaine said:

Ahh but that's not the governor. 

That's max RPM.  

Not sure how to set that... 

Max rpm via the Governor.

 

I thought that what the purpose of the Governor. To hold the rpm in range at full throttle. 

 

Without the Governor it was cranking well over 4000 rpm.

 

Had a thread about it. 
 

The Governor works, and holds max RPM to just under 3600 rpm. 

Edited October 9, 2022 by Heatingman

[Jeff-C175 7,206]

32 minutes ago, Heatingman said:

Governor

 

You may need to move the governor spring to a different hole to change the 'sensitivity'  

[Heatingman 971]

Should the engine speed change between full throttle and idle, or be essentially constant?

 

I assumed the Governor was only inteded to be in play during full throttle.

 

Is this not the case? 
 

When I originally set the Governor per the manual, the full throttle RPM seemed low - around 2200 rpm if Im remembering. 
 

And in the manual, max RPM was listed as 3600. Which is why I fiddled with the governor cross shaft setting to get that 3600 rpm at full throttle.

 

Is that not the correct approach or assumption rather?

 

That 3600 rpm came from the engine manual, which I assumed covered all applications of the motor.

 

Is it possible there is a specific Governor in use for garden tractor applications vs something like a generator which would need the higher rpm?

Note: at the time of initial setting, I never drove it. Just checked rpm with a tachometer.

 

Edited October 10, 2022 by Heatingman

[Heatingman 971]

Ok, so I just reset the Governor per manual. While it definitely does run a lower full throttle RPM, I like it better. Drove it around the yard a little (tested out my head lights to boot) 

 

The motor gives power with load applied as opposed to slowing down with load applied.

 

I also like how it sounds better. More tractory for lack of a better term. Before high rpm sounded a bit import car-ish. 

[Handy Don 14,040]

Governor is in play ALL the time. The human input throttle control connects to one end of a spring and the other end of the spring connects to the governor (the spring and linkages to it vary A LOT on different brands and models of engine).

 

The idea is the human works their control to apply tension to the spring that does two things: 1) sets the speed that makes them happy, and 2) it exactly offsets the governor force at that desired speed.

If the engine tries to go faster, the governor will move the carb throttle plate more closed.

if the engine slows down, the governor moves the throttle plate more open.

All this with the goal of keeping the human happy.

 

The carb throttle plate/linkage has TWO adjustments--one for minimum idle and one for maximum full throttle. These are the outer limits of what the human/governor can ask of the engine. These are typically done with the governor detached or otherwise disabled. 1000 and 3600 RPM normal min and max for engine RPM on these settings.

 

The THIRD setting is to coordinate the spring tension with the governor force. Too little force on the spring and the governor force will run the engine slower than the human wants. Too much, and the governor will overrev the engine.  These adjustment are made differently on different engines. Some have a screw that adjusts the spring tension (some Tecumsehs, for instance). Others have a series of holes in linkage lever arms that apply different tensions (lots of Kohlers).

(The forth setting, as @Jeff-C175 notes, determines how far the throttle plate gets opened and closed for a given movement of the governor arm--a big movement makes the engine react more strongly and vice versa.)  

 

One last item. Air cooled small engines should be operating at the manufacturer recommened RPM for working. For most WH tractors, that is 3,600 RPM. This assures proper cooling and oil circulation. Most of us back off by a couple hundred RPM in deference to the age of the engines, but under 3200 is not a good idea.

Edited October 10, 2022 by Handy Don

[Jeff-C175 7,206]

48 minutes ago, Handy Don said:

but under 3200 is not a good idea

 

Excellent write up Don!

 

When I got my C-125 last year, it would go.....  brrrruuummm! ...... brrrruuummm! .....  brrrruuummm! ...... brrrruuummm! ..... brrrruuummm! ...... brrrruuummm! ..... ad infinitum, and when put under load, would slow way down.  By simply moving the spring down ONE hole on the bracket, it cured that behavior completely.  We're talking about maybe 1/8" in the geometry of things.  Surprised me.

 

That RPM thing though... it's been bugging me since I restored that old generator.  The genset has an 1800 RPM head.  If it was so bad to run them more slowly, it begs the question if it's REALLY that bad to run them more slowly.  I'm just talking about the engine, not the speed of any attachments, or the hydro trannys.  Obviously for those things, yes, you need the speed.

 

It MAY be not quite so that the engines need to run at 3600 RPM for oiling and cooling purposes.

 

 

[Heatingman 971]

Thats what I thought also.

 

if 3600 rpm was what the motor NEEDED, there would be no range in the manual.

 

Just - 3600.

 

1000-1200 would be the low range for oiling and cooling, 3600 would be the top end allowed before overpowering the internal parts and or overheating. 
 

At least thats my interpretation.

 

 

[ebinmaine 72,530]

6 hours ago, Handy Don said:

Air cooled small engines should be operating at the manufacturer recommended RPM

 

 FOR WORKING.

 

For most WH tractors, that is 3,600 RPM. This assures proper cooling and oil circulation. Most of us back off by a couple hundred RPM in deference to the age of the engines, but under 3200 is not a good idea

 

Note that I separated the above words in bold...

Under any load (driving the tractor is a load) the engine needs to be at an RPM to safely (for the engine) sustain the current operation. 

 

Trina and I are almost always at 2400 to 3200 RPM when using any of our tractors.  

 

 

5 hours ago, Jeff-C175 said:

RPM thing though... it's been bugging me since I restored that old generator.  The genset has an 1800 RPM head.  If it was so bad to run them more slowly, it begs the question if it's REALLY that bad to run them more slowly.  I'm just talking about the engine, not the speed of any attachments, or the hydro

 

You've kinda answered your own question there.... The manufacturer of the generator is what sets the speed and HP requirements. 

Perhaps the load of the generator at 1800 is low enough that the manufacturer feels the engine is usable long term at that RPM.  

 

 

 

5 hours ago, Heatingman said:

1000-1200 would be the low range for oiling and cooling, 3600 would be the top end allowed before overpowering the internal parts and or overheating. 
 

At least thats my interpretation

 

IMHO you're headed the right direction there but I'd bring that minimum RPM up a hair. 

 

I'd also add that - in my experience and past teachings - a small air cooled engine should ONLY be run at idle for a short period just before shutdown to prevent excess gasoline from being pulled in through the carb and possibly flooding the next startup. Many engines and many operators would counter that statement.  

 

[lynnmor 7,812]

3 hours ago, ebinmaine said:

I'd also add that - in my experience and past teachings - a small air cooled engine should ONLY be run at idle for a short period just before shutdown to prevent excess gasoline from being pulled in through the carb and possibly flooding the next startup. Many engines and many operators would counter that statement.  

 

 

It's not so much about the next startup, it is about excess gasoline washing down parts and diluting the oil.  Any gasoline entering the engine after the ignition is turned off will not be burned.  Modern fuel injected engines and engines with a shutoff solenoid on a carburetor may stop fuel flow the instant the ignition is turned off preventing the problem and also preventing backfire.

[Handy Don 14,040]

2 minutes ago, lynnmor said:

Modern fuel injected engines and engines with a shutoff solenoid on a carburetor may stop fuel flow the instant the ignition is turned off preventing the problem and also preventing backfire.

These systems also help the engine meet pollution regulations.

[Snoopy11 5,718]

12 hours ago, Heatingman said:

1000-1200 would be the low range for oiling and cooling, 3600 would be the top end allowed before overpowering the internal parts and or overheating

You are correct, @Heatingman.

 

I would concur with Eric though... as my engines never idle below 1,700.

 

12 hours ago, Jeff-C175 said:

The genset has an 1800 RPM head.  If it was so bad to run them more slowly, it begs the question if it's REALLY that bad to run them more slowly.  I'm just talking about the engine

No, it's not. If it was, all of my engines would be dead.

 

My Tillotson 212R and Duromax 457 both idle around 1,800. Both machines spends most of their time running around the funny farm at 1,900-2,250. The bigger the engine, the less RPMs you find that you need for working. I never run the 457 at 3,600 while working... it just isn't necessary.

 

Having said all of that, the way I run my engines, I do pull rod caps, check valve lash, and examine for carbon buildup on cylinder heads, etc. My engines consistently check out, no rod bearing wear, minimal carbon deposits...

 

I never run hydro machines at idle unless the hydros themselves are disengaged.

 

I should also state that I do run my Kohler k341 at idle, and below 3,600 the majority of the time. I only find it necessary to crank it up to 3,600 when I am on the move. Otherwise, pulling loads, etc... I don't find it necessary to run it up to 3,600, burn more fuel, dump more heat into the engine, etc.

 

Just my experience... your mileage may vary...

 

Don