How do I set engine RPM

[Jim_M 178]

http://www.justanswer.com/small-engine/4ap0n-hi-john-deere-stx38-kohler-12-5-removing-carby.html

http://www.kohlerengines.com/onlinecatalog/pdf/tp_2402_a.pdf

 

page 5.14 in the service manual.

Edited June 13, 2014 by Jim_M

[Fordiesel69 232]

Thanks, I was wrapping it wrong.  I will try again per the PDF.

 

Also for the member trying to adjust the gov cross shaft.  You do NOT do that during a typical speed adjustement.  The cable, and springs get adjusted.  The cable for speed, the springs for sensitivity.

[Jim_M 178]

How to Set the Governor Adjustment - Top of page

If your engine revs with no closing of the throttle shaft, or surges, then the governor is probably out of adjustment. To set the governor on a Kohler (or virtually any engine)...

1. Install all the throttle linkages, governor parts, etc., in their respective places.
2. Loosen the bolt that clamps the lever to the governor cross-shaft that protrudes out of the engine block.
3. With the throttle plate blocked in the wide open position, rotate the cross-shaft counterclockwise until it stops. Now tighten the bolt.
4. That's all that's to it! But if this doesn't fix the problem, then perhaps a governor part inside the engine is damaged or the screws came out of the throttle plate, where it fastens to the throttle shaft.
5. And it doesn't matter how long or short the link is because the governor is adjusted by the clamp on the cross shaft. Actually, I don't know why Kohler made the link adjustable. It serves no purpose to lengthen or shorten it.
6. You can also go here for further details and pictures: http://cubfaq.com/govadjust.html.

And to set the high rpm governored speed, place one end of the governor spring in the middle to lower hole in the "L" shaped governor lever, and place the other end of the spring in either the top or second hole from the top in the short lever that's located under the carburetor or on the flywheel shroud. It's best to use a [Dixson] small engine tachometer to determine the exact rpm to prevent over-revving of the engine, which could cause the connecting rod to break. (Double the reading on the [Dixson] tachometer on engines with camshaft-operated ignition points.) The high speed governor limit for a stock engine is set at 3,600 rpm. For a stock pulling engine, set it at 4,000 rpm, or whatever sanctioning rules require.

Do not mistakenly rotate the cross shaft clockwise (opposite rotation than what it shows in the drawing above) until it stops, tighten the clamp and then run the engine! Doing this could cause the lever (see below) to jam into the governor flyweights, breaking off the lever and/or possibly destroying the governor gear assembly.

If the governor cross-shaft (the shaft that protrudes from the block) gets bent due to rough handling of the engine, and if it's not bent too bad, just use a hammer to straighten it. It's made of mild steel. But if it's bent severely and breaks off, it must be replaced. If this happens, usually the bushing/nut (Kohler part # 235476) will break and it will need to be replaced, too. Or, if the above adjustment was attempted, and the governor shaft keeps rotating without stopping, this means the flat lever on the shaft has broken off. This will allow an engine to operate dangerously at wide open throttle at all times.

To fix either of the above, another governor shaft (Kohler part # A23525601S) must be installed. To install another shaft, the entire engine must be completely disassembled. This means EVERYTHING inside the engine block (crankcase) will need to be removed. And then the replacement shaft can installed from inside the crankcase. But before the old shaft is removed, the bronze bushing/nut on the outside must first be removed. The governor gear assembly doesn't have to be removed. The shaft lifts out from inside the crankcase and is installed in reverse order of removal. And it'll be a good idea to place a small bead of weld on the flat lever to secure it to the shaft to prevent future breakage. (I think this is something that Kohler should have done.) I realize that this is a lot of work just to replace a small [important] part, but it must be done in this way. There is no other way to replace it.

This is for the K series engines. The command is a whole different procedure. I posted a link to the single cylinder Command service manual.

[bizzo15 52]

This is for the K series engines. The command is a whole different procedure. I posted a link to the single cylinder Command service manual.

Jim,

 

Thanks for posting that link, I already have the manual for the command and that's what I followed for the "initial adjustment"  which now that I re read isn't my issue at all.  My issue is the engine is not running at 3600rpm when I have the throttle lever on full throttle.  The governor itself seems to be doing it's job.  What do I need to adjust to get the rpms in their peak range at full throttle?

Edited June 13, 2014 by bizzo15

[Jim_M 178]

There is a small screw that limits the travel of the throttle. Look at the arms attached to the gov. spring. Should be a little screw somewhere that limits how far one of those arms can move. I can't find a good picture of it anywhere.

 Before you do anything with the governor adjustment, make sure your throttle cable hasn't slipped. If the end of the previously mentioned arm isn't hitting the stop screw then you need to move the throttle cable in it's clamp until it does hit. If it's already hitting the screw, you'll need to adjust the screw.

Edited June 13, 2014 by Jim_M