Generac — Governor Running Adjustment
Adjustments · Mechanical governor
From a Generac service manual covering: GN-190, GN-191, GN-320, GN-360. Check it applies to your exact model before use.
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Before you start
- DO NOT EXCEED RPM SPECIFICATION.
Procedure
- For AC generator applications, disconnect or turn OFF all electrical loads; for non-generator applications, turn OFF the equipment.
- Set the idle control switch to OFF (if equipped).
- Start the engine and let it warm up and stabilize at no-load.
- For AC generators, connect an AC frequency meter; 60 Hz reading should be 61.5-63.5 Hertz and 50 Hz should be 50.5-51.5 Hertz.
- Turn the SPEED ADJUST NUT on the governor until frequency or rpm is within limits.
- If unstable, turn the carburetor IDLE SPEED SCREW until the engine stabilizes, adjusting 1/8 turn at a time.
- Apply a load and adjust the IDLE SPEED STOP SCREW for best operation and highest rpm under load.
- Turn off all loads and check the no-load governor setting; readjust if necessary.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 60 Hz no-load: 61.5-63.5 Hertz
- 50 Hz no-load: 50.5-51.5 Hertz
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.