Wagging Governor

[AJB0009]

2011 Ariens 21" push mower. Kohler Courage XT-6 engine.
Issue seems to have started all of a sudden.
When the engine is running, the governor arm goes back and forth like a dog's tail wagging. Warm or cold, idling or under load; does not seem to matter.
This mower has seen a lot of use, but I've taken very good care of it. It is clean and well maintained.
Some people love to hate on these, but it has been nearly flawless for me. The crank case base gasket started leaking a quite a bit, so I changed it. That is really all that I remember. Only ever had E-0 in it.
Has an auto choke with a bi-metallic spring on the muffler and a vacuum diaphragm. I tested both of those, they are working as they should.
At cold start, one pull gets it running and you can watch the choke plate slowly open to full after a few minutes.
Spark plug is clean. Zero oil consumption or smoke.
Only issue is the throttle plate goes back and forth from the governor.
Thoughts on a root cause?

 

[yeehaw1960]

Searching for gas. Doesn't matter how well you take care of an engine, it will probably sludge up eventually. Pull carb and clean it, and drain every drop of fuel from system. If it's a lot, put it in your daily driver (assuming your vehicle has at least a quarter tank of gas in it already). As a last resort, hit up Amazon and get a new carb (rarely over $20). Take pictures of the carb before looking at Ebay or Amazon. The choke configurations vary.

 

[blufeb95]

I haven't ever adjusted the governor on a kohler but most small engine have some way to adjust the tension on the governor wither by bending a tab that the governor spring goes into or have a screws that puts more tension on a torsion spring like tecumseh governors, the spring is probably stretched with age and just needs more tension.

 

[mk378]

That's the low speed circuit. With no load, if you manually pull the governor/throttle link all the way to slow, it should run smooth and slow. If it dies out you need to clean the low speed jet in the carb. You could also try turning the slow stop screw on the throttle plate higher.

Tightening the big spring so much that it increases the governed speed above spec (Not recommended because the piston rod will eventually break), can also cause surging.

 

[Wrenchturner44]

AJ, Does the air filter box have any oil residue in it? If it does, you may have clogged PCV system. A clogged system may not interfere with governor operation directly, but it can cause engine to surge.

 

[Wrenchturner44]

http://www.kohlerengines.com/engines/onlinecatalog/pdf/sm_14_690_01.pdf

 

[wag123]

Surging (hunting) is indicative of a restriction in the carburetor's low speed (idle) circuit, either a bit of dirt or varnish. You need to remove the carburetor and clean-out all of the passages (adding something to the gas won't help). The fuel passages are very small in the low speed circuit and easily restricted.

 

[blufeb95]

If you look at this video, and the pinned comment from the guy who posted it, the governor spring getting out of adjustment is common, in the video to me when the engine was running to slow it looked like it was surging because there was no tension on the governor arm and the throttle can flap, without a tachometer, if you bend the tab to put more tension on it, I'd do it just to the point it puts some tension on the spring and not much further, it may be running a little slow but it should smooth it out.