It's easier if you put a mark on the governor first like in the image below.
Governor Arm Adjustment Procedure (Small Engine / Mower)
As you found out when loosening the governor arm clamp bolt on the governor shaft, the governor system allows very minute rotational adjustment. Small movements of the governor arm can result in noticeable RPM changes once the bolt is retightened.
Adjustment Notes
After repositioning the governor arm and tightening the clamp bolt, engine RPM will change based on how far the arm is rotated.
Because the adjustment range is small, it can be difficult to judge how much movement has occurred.
Recommended Marking Method
To make accurate and repeatable adjustments:
Before loosening the governor arm clamp bolt, use a scribe, small screwdriver, pick, or sharp knife.
Scribe a reference line across the end of the governor shaft and onto the governor arm, or along the side of the governor shaft if the governor arm sits a fair distance down from the end of the shaft.
This reference mark provides a visual indicator of the original position. Note: The metal does not need to be scratched—applying a black marker (texta) first will make the reference line clearly visible.
Benefits
Allows you to clearly see how far the governor arm has been moved.
Makes fine RPM adjustments easier and more controlled.
Provides a reliable reference point for future governor adjustments.
Final Adjustment
After repositioning the governor arm:
Tighten the clamp bolt securely.
Start the engine and verify RPM.
If further adjustment is required, use the reference mark as a baseline for incremental changes.
