Kohler CH20S Poor performance (Kubota)

Discussion in 'Mechanic and Repair' started by hukturn, Mar 23, 2011.

  1. hukturn

    hukturn LawnSite Member
    Messages: 1

    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 ½ 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
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Hello hukturn,

    That was a very informative post you made there, But.... You failed to post the engine spec number. This number will show us exactly what components are used on your engine, I have a idea but need to verify before I go further.
  3. southgalawns

    southgalawns LawnSite Member
    from ga
    Messages: 110

    so it ran fine and perfect without gas cap?
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    He "Ran w/out gas cap" thus verifying it's not a gas cap vent issue.... Thumbs Up
  5. aarons lawn

    aarons lawn LawnSite Member
    Messages: 107

    next time get the one that takes red or green fuel
  6. Snyder's Lawn Inc

    Snyder's Lawn Inc LawnSite Platinum Member
    Messages: 4,530

    does it have the smart spark box

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