Kohler command 20 running rich

[AKBOB]

My MAXIV runs rich and has dark sooty exhaust and spark plugs. All I can find is an idle speed adjustment screw. I don't see any Idle speed or high speed adjustments on the carburetor. How do you adjust the mixture?

Bob

[msafi65]

The idle mixture screw is usually under a pressed in cap right next to the fuel shut off solonid. You should use left hand drill to drill and pull the cap. Right hand drills usually break through the cap and drive the idle air screw into the seat and can damage it. What I usually find on these if they are very rich is fuel in the oil, either from carb iceing or a bad fuel pump dumping fuel into the crankcase.

[dirtdobber]

Akbob I'm not familiar with this engine, but just for the heck of it I have seen a couple of other things make an engine run rich (other than the mixture screw). Trash keeping the float/needle from closing is one. The other is a faulty accelerator pump circuit (fuel circuit, not electrical) if your carb even has one. I saw this on a zero turn mower once - the accelerator pump is vacuum operated and gives the engine a little extra shot of fuel when rpm's are demanded. The if the little diaphragm fails then fuel could continuously be drawn into the engine.

Sorry for wasting your time if this doesn't apply to your engine.

[AussieMax]

The idle mixture screw really only affects the mixture at idle. A dirty air filter will cause it to run rich also . The carb sounds like it will need a good clean as it has a number of air jets that help it to atomise the fuel. If these get restricted it will run rich. A good carb cleaning fluid and a bit of time and patience and it should be good as new.