Cummins/Onan 12.5 RDJC / 15.0 RDJC — Governor Speed Adjustment
Adjustments
For the Cummins/Onan 12.5 RDJC / 15.0 RDJC, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan 12.5 RDJC, Cummins/Onan 15.0 RDJC, Cummins/Onan RDJC
Procedure
- Turn the governor speed adjusting nut clockwise (more spring tension) to increase rpm.
- Turn the nut counterclockwise to reduce governed speed.
- Use a stroboscope or a frequency meter to make this adjustment.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 1800 rpm generates 60 hertz on a 4 pole generator
- Preferred engine speed does not vary more than 3 hertz from no-load to full-load operation
Full service-parts list: Cummins/Onan RDJC →
Source: Cummins/Onan operator's 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.