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Home›Repair guides›Cummins/Onan›Gasoline Carburetor Adjustment

Cummins/Onan 4MCCK / 605MCCK — Gasoline Carburetor Adjustment

Adjustments

For the Cummins/Onan 4MCCK / 605MCCK, from the Cummins/Onan service manual.

Applies to: Cummins/Onan 605MCCK, Cummins/Onan MCCK, Cummins/Onan MCCK engine

Before you start

  • Don't force the needle valves against their seats; this will bend the needle.

Procedure

  1. If the carburetor is completely out of adjustment, open both needle valves 1 to 1-1/2 turns off their seats to permit starting.
  2. Allow the engine to warm up with the ignition system and governor adjusted.
  3. Apply a full load; turn the main adjustment in until speed drops slightly below normal.
  4. Turn the needle out until speed returns to normal.
  5. With no engine load, turn the idle adjustment out until speed drops slightly below normal.
  6. Turn the needle in until speed returns to normal.

Full service-parts list: Cummins/Onan 605MCCK →, Cummins/Onan MCCK →

Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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