Cummins/Onan — Governor and Speed-Booster Adjustment
Adjustments
From a Cummins/Onan service manual covering: 4CCK, 5CCK, 5CCK-150R, 5CCK-3CR. Check it applies to your exact model before use.
Applies to: Cummins/Onan 4CCK, Cummins/Onan 5CCK, Cummins/Onan CCK engine
Before you start
- Too much sensitivity causes hunting
Procedure
- Run plant 15 minutes under light load to normal operating temperature.
- Adjust carburetor main jet for best mixture at full rated load.
- Adjust carburetor idle needle with no load connected.
- Adjust length of governor linkage and check linkage and throttle shaft for binding.
- Adjust governor spring tension for rated speed at no load with booster disconnected.
- Adjust governor sensitivity for closest regulation without hunting.
- Recheck the speed adjustment.
- Set carburetor throttle stop screw and set the vacuum speed-booster.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- AC speed regulation per voltage and speed charts
Full service-parts list: Cummins/Onan 4CCK →, Cummins/Onan 5CCK →
Source: Cummins/Onan 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.