Cummins/Onan — Breaker Points Adjustment
Adjustments · Ignition breaker points
From a Cummins/Onan service manual covering: 2.5 MAJB-53BR, 2.5 MAJB-53CR, 3.0 MAJB-1R. Check it applies to your exact model before use.
Applies to: Cummins/Onan MAJ, Cummins/Onan MAJB engine
Before you start
- Disconnect battery ground cable before servicing
Procedure
- Disconnect the negative (-) battery cable at the battery terminal.
- Remove the breaker box cover.
- Disconnect the breaker box control and magneto leads.
- Connect an ohmmeter or continuity tester to the hot and ground sides of the breaker points.
- Remove the spark plugs and turn the rotor through-bolt clockwise until the points begin to open.
- Adjust the points to open when the flywheel timing mark aligns with the 25 degree mark on the gear case cover.
- Replace the point box cover, spark plugs, and spark plug leads.
- Connect the negative (-) battery cable to the negative battery terminal.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Timing 25 deg BTC
- Adjust with engine static and cold
Full service-parts list: Cummins/Onan MAJ →
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.