Kohler CH20S Poor performance (Kubota)

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  #1  
Old 03-22-11, 05:35 PM
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Kohler CH20S Poor performance (Kubota)

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 ˝ throttle, but still shuts down over time and/r under load (ie; mower blade). I would not describe the overall idle as “rough” but it is also not “smooth”. 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
 
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Old 03-22-11, 07:55 PM
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Kind of sounds like the float sticking periodically, or possibly a clogged bowl vent causing excess fuel to burp into the carb periodically.
 
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Old 03-23-11, 07:25 AM
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Thanks, Cheese! Is it reasonable to rule out ignition problems, considering my symptoms? I've thought about pulling the carb and cleaning. But, hesitating as I try to rule out other things.
 
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Old 03-23-11, 09:35 AM
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I don't know that I'd completely rule ignition out as a possibility, but it's not where I'd start looking.
 
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