Engine running rough, governor going crazy (video)

[mlapaglia]

I have a kohler command cv25s engine that runs all crazy. when i slowly move the throttle up to high i can get it to run without surging, but after i start the blades it begins surging again. here's a short video demonstrating what's going on:

if i reach out and grab the governor arm and hold it in place the engine runs great!

i've already tried a knock-off carburetor from amazon, and a genuine used carburetor from ebay, both have the exact same issues as the original carburetor.

here's the fun part, the amount of surging changes from day to day, sometimes i can choke it a bit and get it to run without surging and i can mow my yard. other days no such luck.

idk what to do anymore!

 

[ILENGINE]

Adding choke and smoothing out is usually a symptom of a carb lean issue, But that only works part of the time in your case. By holding the governor arm and running smooth points to a governor issue. I am personally leaning toward a governor issue. Something you could try is the governor arm has several holes for the governor spring. Try moving the spring up toward the rod one hole and see what happens. That would reduce the sensitivity and may fix the issue.

Also running and testing without the air filter in place can cause a slight lean issue which may also contribute to the surging.

 

[mlapaglia]

alright, i took the main jet, which has "140" written on it (which i'm guessing means 1.40mm), and reamed it out to 1.5, 1.8, then 2.0mm, surging happened on all of them, at 2.0mm i started getting black smoke out the exhaust when i would engage the blades. I would agree it's probably not a lean issue. luckily i have a bunch of backup jets now lol.

i moved the governor spring up to the highest and down to the lowest, the surging happens on all of them