Cummins/Onan 4.0CCK Generator Set

Tools: flat thickness gauge

1. Remove cover screws
2. Remove spark plugs
3. Turn flywheel clockwise about 1/4 turn after top center
4. Loosen screws A and turn cam B until gap is .020 in.
5. Retighten screws and recheck gap
6. Replace spark plugs and cover

Tools: idle adjustment tool

1. Run engine at no load
2. Turn idle needle in until engine slows considerably
3. Turn out until engine runs smoothly

Tools: main adjustment wrench

1. Connect full load
2. Turn main needle out about two turns
3. Turn in slowly until engine loses power
4. Turn out slowly until smooth at full power
5. Do not open more than 1/2 turn beyond maximum power

1. Loosen two cover retaining screws
2. Turn cover clockwise for less choking action
3. Turn counterclockwise for more choking action
4. Retighten cover screws

Tools: 1/16 in. diameter rod

1. Insert 1/16 in. rod through shaft hole into mounting flange notch
2. Loosen choke lever clamp screw
3. Adjust choke lever so plate is closed or not more than 5/16 in. open
4. Tighten screw and remove rod

Tools: Flat thickness gauge, File or fine stone

1. Remove the two screws and the cover on the breaker box.
2. Remove the two spark plugs so engine can be easily rotated by hand.
3. Turn flywheel clockwise approximately 1/4 turn after top center (TC).
4. Loosen screws (A) and turn cam (B) until point gap measures .020 in with a flat thickness gauge.
5. Retighten screws (A) and recheck gap.
6. If points are slightly burned, dress smooth with a file or fine stone; if burned and pitted, replace with a new set.
7. Replace spark plugs and breaker box cover.

Tools: Carburetor adjustment wrench

1. Make all adjustments with the engine at normal operating temperature.
2. For main jet, connect a full or nearly full load; turn main adjusting needle out about two full turns.
3. Turn needle in slowly until engine begins to lose power and speed, then out slowly until engine runs smoothly at full power and speed.
4. If hunting occurs, open main adjusting needle a little more (no more than 1/2 turn beyond maximum power).
5. For idle jet, with no load, turn needle in until engine loses considerable speed, then out until engine runs smoothly.

⚠ Too much sensitivity will cause hunting

Tools: voltmeter or frequency meter

1. Check voltage and speed at no load and full load
2. Shift adjusting clip toward governor shaft to increase sensitivity
3. Shift clip toward outer end of governor arm to decrease sensitivity
4. Avoid hunting condition
5. Recheck speed adjustment

Tools: voltmeter or frequency meter

1. Run unit 15 minutes under light load
2. Disconnect or hold booster inactive
3. With no load, adjust governor spring tension to rated speed and voltage
4. Recheck speed adjustment

⚠ Too much sensitivity adjustment will cause alternate increase and decrease of engine speed (hunting).

Tools: Voltmeter or frequency meter, Tachometer

1. Run unit about 15 minutes under light load to reach normal operating temperature.
2. Adjust carburetor main jet for best fuel mixture at full rated load.
3. Adjust carburetor idle needle with no load.
4. Adjust governor linkage length and check linkage and throttle shaft for binding or excessive looseness.
5. Adjust governor spring tension for rated speed at no load with booster disconnected.
6. Adjust governor sensitivity (shift clip toward governor shaft to increase sensitivity).
7. Recheck speed adjustment, set carburetor throttle stop screw, and set vacuum speed booster.

Tools: continuity test lamp

1. Connect continuity test lamp across breaker points
2. Turn crankshaft counterclockwise until points close
3. Slowly turn clockwise; lamp goes out as points break at 19° BTC

Tools: timing light

1. Connect timing light
2. Remove timing hole plug
3. Start engine and check mark aligns with 19° BTC
4. Loosen breaker box screws and move left to advance or right to retard
5. Start engine and verify
6. Tighten screws and replace timing plug