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Home›Repair guides›Generac›Carburetor Idle Jet Adjustment

Generac — Carburetor Idle Jet Adjustment

Adjustments

From a Generac service manual covering: GN-190, GN-220, NP-30G, NP-40G. Check it applies to your exact model before use.

Applies to: Generac NP-30G, Generac GN-190 / GN-220 engine, Generac GN-190 or GN-220 engine

Before you start

  • Do NOT adjust the fuel-air mixture excessively lean; an excessively lean mixture can result in engine damage.

Procedure

  1. Turn the idle jet inward (clockwise) until it just contacts its seat; do not force.
  2. Turn the idle jet outward (counterclockwise) 1-1/8 turns.
  3. Start the engine and let it warm up for about five (5) minutes.
  4. With engine running at no-load, turn the idle jet clockwise (leaner) until engine speed starts to decrease or fluctuate.
  5. Turn the idle jet counterclockwise (richer) until engine speed decreases or black smoke comes from the exhaust.
  6. Very slowly turn the idle jet clockwise (leaner) until engine speed just stabilizes or black smoke just stops.

Specs & values

  • Initial idle jet adjustment: 1-1/8 turns out from seat

Full service-parts list: Generac NP-30G →

Source: Generac 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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