Cummins/Onan E125 Generator Set

Tools: feeler gauge

1. Engine must be at room temperature.
2. Remove the valve rocker cover and spark plug.
3. Turn engine over until piston is at COMPRESSION TOP DEAD CENTER.
4. Check intake and exhaust valve lash with a feeler gauge.
5. Loosen locknut and turn lash adjusting screw until specified lash obtained.
6. Tighten locknut and recheck lash.

Tools: 1/8 inch drill bit, wrench

1. Shut off engine, remove air cleaner outer cover and filter element.
2. Loosen choke rod swivel clamp screw.
3. Lock throttle control lever with pin (1/8 inch drill bit) so pin acts as stop for choke lever.
4. Push choke rod towards carburetor to fully open choke.
5. Rotate choke lever towards carburetor until it bears against pin stop, tighten swivel clamp screw.
6. Remove lock pin and check choke linkage operation. Replace damaged components.
7. Reassemble air cleaner.
8. Adjust throttle and choke control cables.

Tools: 1/8 inch drill bit, wrench

1. For single-cable: shut off engine, loosen throttle cable clamp.
2. Lock throttle lever with pin (1/8 inch drill bit).
3. Push speed control lever to high speed position.
4. Hook cable wire into throttle lever, pull out slack, tighten clamp. Remove lock pin.
5. For two-cable: repeat steps 1-3, then push choke knob to full-open.
6. Hook choke cable wire into choke lever, push choke rod towards carburetor, pull out slack, tighten clamp.

⚠ Adjusting the engine speed to a value above that specified by the equipment manufacturer could cause the equipment to operate at speeds in violation of Federal and State Standards for Safety for the equipment.

⚠ Moving parts can cause severe personal injury or death. Take care when measuring engine speed with a tachometer and follow the meter instructions. You must be a qualified mechanic.

Tools: tachometer

1. Normally no need to adjust engine speed. Instructions are for equipment manufacturer. Attempt only by qualified mechanic using accurate tachometer.
2. Set low-idle and high-idle speeds to values specified in equipment Operator's Manual. If absent, adjust low-idle to 1,100 RPM and high-idle to 3,400 RPM.
3. Start engine, observing all equipment manufacturer's instructions and precautions.
4. If throttle cable already connected, loosen clamp at engine and back out low-idle speed stop screw so speed stop screw on carburetor touches its stop. Adjust engine speed to 1,000 RPM with carburetor
5. Turn low-idle speed stop screw to obtain specified low-idle speed.
6. Move engine throttle link up against its stop tang and hold it there while bending tang as necessary to obtain specified high-idle speed.
7. Hook engine throttle link with throttle cable, pull slack out of throttle cable and tighten clamp. Check for full, smooth movement of engine throttle link between its two stop positions when equipment

⚠ Adjusting engine speed above equipment manufacturer specification may violate Federal and State safety standards.

Tools: accurate tachometer

1. Start engine and move throttle lever to lowest speed position.
2. Adjust low-idle speed stop screw on carburetor to specified low-idle speed.
3. Move throttle lever to highest speed position.
4. Loosen high-idle stop plate clamping screw and rotate plate to specified speed; retighten.
5. For lever controlled engines adjust lever stop screw instead.
6. Check full smooth movement of throttle control arm between stop positions.

⚠ Disconnect spark plug and battery negative cable before adjusting the governor.

1. Loosely assemble governor arm to governor shaft and start the lock nut.
2. Re-attach link to governor arm and carburetor; replace worn clips.
3. Push top of governor arm toward carburetor until it stops and hold.
4. Check governor spring pulls carburetor throttle to wide open.
5. Tighten lock nut; ensure governor shaft rotates clockwise against internal parts.
6. Tighten to Section 3 torque specifications.

⚠ Accidental starting can cause severe personal injury or death.

1. Stop engine and disconnect spark plug and battery negative cable.
2. Push choke knob to full open-choke; set throttle lever to lowest speed.
3. Loosen cable clamp at engine bracket if necessary.
4. Hook cable wires into hook holes in choke and throttle control arms.
5. Rotate control arms clockwise, hold against stops, pull out cable slack, tighten clamp.
6. Check smooth movement and full travel of choke knob and throttle lever.
7. Reassemble air cleaner and reconnect spark plug and battery.

⚠ Reversed battery connections or operation without a battery will damage the voltage regulator and/or alternator stator.

Tools: multimeter (Simpson 270)

1. Check battery voltage with engine not running; charge if out of specification.
2. With engine running, check voltage regulator output at battery terminals.
3. Disconnect stator leads from regulator and test stator AC output.
4. Shut down engine and check resistance between each stator lead and ground.
5. Check stator resistance across stator leads with ohmmeter.
6. Replace stator if resistance out of specification.
7. Replace flywheel assembly if stator resistance is correct but output low.

1. Pull choke knob to full-choke position to close choke plate.
2. Remove outer cover; wipe away loose dust and debris.
3. Remove mounting nut, inner cover and air cleaner element.
4. Wipe dust and debris from the air cleaner base.
5. Install new paper element and secure with inner cover and mounting nut.
6. Tighten nut 1-1/2 turns after seating it on the cover.
7. Reinstall foam wrapper and outer cover.

1. Refer to Table 2 for scheduled foam wrapper maintenance and air cleaner element replacement. See Figure 4.
2. For foam wrapper only: do not remove inner air cleaner cover. Remove and wash foam wrapper in water and detergent.
3. Squeeze foam wrapper dry like a sponge. Rinse with clean water and allow to dry.
4. Coat wrapper evenly with one tablespoon (14 grams) of SAE 30 engine oil. Knead oil into wrapper and wring out excess oil.
5. Install foam wrapper over paper air cleaner element by stretching it over inner cover. Completely cover all exposed paper pleats.
6. Replace foam wrapper when it becomes torn or stretched.
7. For element replacement: pull choke knob to full-choke position to close choke plate. Remove outer cover and wipe away loose dust and debris.
8. Remove inner air cleaner mounting nut and cover.
9. Remove air filter paper element and foam wrapper from engine. Wipe off dust and debris from air cleaner base.
10. Install new paper element and secure with inner cover and mounting nut. Reinstall foam wrapper and outer cover. Reconnect crankcase breather tube.

1. Remove the through-bolt and cover.
2. Reassemble with a new air filter element and wrapper.
3. Do not over-tighten the through bolt.

⚠ Batteries give off explosive gases; do not smoke or allow flames or sparks near batteries

⚠ Battery electrolyte can cause severe eye damage and skin burns

Tools: Terminal puller tool, Battery hydrometer, Goggles, Rubber gloves, Protective apron

1. Keep the battery case clean and dry.
2. Make certain battery cable connections are clean and tight.
3. Remove the negative (-) cable first and connect it last.
4. Remove corrosion with an ammonia or baking soda solution; flush with clean water.
5. Add distilled water to each cell to the split-level marker if not maintenance-free.
6. Check specific gravity of each cell with a hydrometer; charge if below 1.215.
7. Stop charging when specific gravity reaches 1.260 at approximately 80° F (27° C).