Generac — Engine Governor Adjustment (Mechanical)
Adjustments · Mechanical governor
From a Generac service manual covering: IM100G, IM80G, NP100G, NP80G. Check it applies to your exact model before use.
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Procedure
- Connect an AC frequency meter across the generator's AC output leads.
- Turn OFF all electrical loads; initial adjustments at no-load.
- Start the engine, let it stabilize and warm up.
- Check no-load AC frequency: 60.5-63.5 Hertz (60 Hz units); 49-51 Hertz (50 Hz units).
- Loosen NO-LOAD BUMPER SCREW lock nut, then loosen the bumper screw so the governor is not pre-loaded.
- Adjust NO-LOAD SPEED ADJUST SCREW to obtain 61.5 Hertz (60 Hz units) or 50.0 Hertz (50 Hz units).
- Adjust NO-LOAD BUMPER SCREW to obtain 62 Hertz (60 Hz units) or 51 Hertz (50 Hz units).
- Apply load equal to rated capacity; if frequency drops below 58 Hertz (60 Hz) or 49 Hertz (50 Hz), adjust DROOP ADJUSTMENT downward.
Tools required
- AC frequency meter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- No-load 60.5-63.5 Hertz (60 Hz); 49-51 Hertz (50 Hz)
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.