Kohler CH20S not operating correct

[hukturn]

Kohler CH20S w/1bbl carb (in a Kubota GR2000) will not idle. Governor will adjust (choke out) periodically (about every 10 seconds or 15 seconds w/choke on). When this happens, engine chokes down to near stop but recovers, unless under load (blades engaged, hard turns). Some light black smoke when first starting and/or when I throttle up quickly. Engine/carburetor seems to have the most difficulty when at operating temperature and/or when under load. Runs/idles fine when cool (at startup) but has problems after about 5min of running. Runs/idles fine for longer period of time when at low idle. Seems to also have difficulty maintaining RPM when travelling up/down hills. I am not operating at high altitudes. Will run for longer at ｽ throttle, but still shuts down over time and/r under load (ie; mower blade). I would not describe the overall idle as 途ough but it is also not 都mooth? Automatic choke was not opening fully (possibly 20degree butterfly), so I added a spring to allow full (90degree butterfly) opening when choke lever is disengaged. Thoughts?

Some things already done;
Changed plugs
Checked spark and has nice blue fire
Adjusted the float levels (no cracks/holes)
Adjusted external governor spring (there is tension on governor rod, so it is engaging)
Good fuel flow up to carburetor (and bowls have fuel)
Slow speed jet O-Rings are good
Oil level is good
Removed fuel filter and air filter for testing during repair (still problems)
New gas w/carb cleaner additive
Ran w/out gas cap

 

[Scotty370]

Wild guess- Cracked Head that the crack get wider at 'heat up'? Or head gasket? Like I said, wild guesses!!!!!!~S

 

[hukturn]

I would guess not, but could easily be wrong. I would have thought a cracked head would introduce oil into the combustion chamber and yield blue smoke. Probably also would cause the problem at 1/2 throttle. But, probelms only exist when at full throttle or under load (ie; mower blades).

I'd also suspect that I would hear a "pffft" if the gasket were blown.

Thoughts?

 

[mrmikey]

I had a somewhat similar problem with my ole 17 Kohler, it was the governor adjustment.
Me, having a good but short memory can't remember the correct procedure. It involved loosening the arm to governor shaft and moving the carb linkage but I can't remember the correct procedure. I made notes but &*&*%$ can't even find them.....Mike

 

[Kernopelli]

Uhhhh...bad memories. I've had my fair share of CH20 woes. I wish I could give you some straight answers but can't. I had similar issues but I was able to adjust the majority out through governor spring adjustments....obviously not the case for you. Wondering if it could be a bad coil that is malfunctioning when it gets hot. Seems like I remember some possible issues with the "smart spark" as well.The good advice I can give is that Kohler's website has excellent online service manuals for all their engines and you may be able to find some answers there. I have also gotten great assistance from the Kohler gurus on Lawnsite.com 's mechanic and repair forum. Several longtime Kohler techs like "Restrorob" are trolling there all the time and they are very knowledgeable and helpful. If you post the same info as you did here I'm certain they will answer you quickly and get you headed in the right direction.

 

[Just Bill]

I had the same type of problem.
I used a double dose of walley world carb & inj. cleaner.
After 3 or 4 tanks it ran better than it ever had.
Its a cheap fix that worked for me, you just have to be patient.

 

[kub32guy]

I had similar issues on briggs engine, turned out to be some dry rotted lines. Didn't notice it till I looked closely. I bought about 8' of rubber fuel line and replaced them all, and runs fine now. Just a thought.

 

[mostly_gas]

What color is the spark plug? Plug color will tell you if you are chasing a lean or rich condition. Dark brown to black = rich, light to white = lean. I would suggest est of mixture ok before adjusting governor.

 

[Powerstroke777]

Might want to do a compression test. But a bad coil will give the symptoms you are discribing, as an earlier post suggested.

 

[Soundguy]

on a tractor I would say fuel obstruction / starvation.. the gov revs it up.. that increases felt manifold vac.. puls some fuel in.. it overspeeds, corrects down, then dies again.. classic fuel starvation hunt.

soundguy

 

[RobertBrown]

Take that thing and run it at night or in the dark and see if the exhaust pipe is glowing red, indicating a lean condition and a partially clogged jet. I think you have a carb problem and I would bve interested in knowing any circumstances leading up to this malfunction. Has this machine been sitting all winter?

 

[Treemonkey1000]

Another thing to try and look for is get some spray carb cleaner and hose off all of the governor linkage and throttle linkage. If you can get it running long enough spray the carb cleaner around the carb to head intake gasket to see if it affects how it runs at all. All of the heat can cause gaps between the intake and carb. And all of the other checks of gas tank filters and internal carb filters. Like others said was check your plug color. Does it run better with the air filter off?