Generac GT-990 — Check and Adjust Engine Governor (Single Cylinder Units)
Adjustments
For the Generac GT-990, from the Generac service manual.
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Procedure
- Loosen governor clamp bolt.
- Hold governor lever at wide open throttle; rotate governor shaft clockwise fully; tighten clamp bolt to 70 inch-pounds.
- Start generator and let stabilize at no-load.
- Connect frequency meter across AC output leads.
- Turn primary adjust screw to obtain 61.5 Hz.
- Turn secondary adjust screw to obtain 62.5 Hz.
- Check AC voltage; adjust voltage regulator if needed.
Tools required
- frequency meter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Governor clamp bolt 70 inch-pounds (8 N-m)
- Primary adjust 61.5 Hz
- Secondary adjust 62.5 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.