Generac OHV Engine

Tools: socket, feelers/gauges

1. Verify the piston is at top dead center (TDC) of its compression stroke (both valves closed).
2. Remove four (4) screws from rocker cover.
3. Remove rocker cover and rocker cover gasket.
4. Loosen rocker arm jam nut. Turn adjustment screw in to decrease clearance or out to increase clearance.
5. Hold socket steady and tighten lock nut to specification; check clearance and make minor adjustments.
6. After tightening jam nut, recheck valve clearance to make sure it did not change.
7. Install rocker cover, gasket and four screws; tighten to specifications.

⚠ Ensure all material is clear of the alternator before proceeding.

Tools: VOM

1. Remove cover from end of alternator assembly.
2. Remove two screws holding down the voltage regulator (AVR).
3. Leave AVR connected to stator and brushes.
4. Set VOM to measure AC voltage.
5. Connect VOM across a 240VAC socket.
6. Set START-STOP-RUN switch to START.
7. Turn adjustment screw clockwise to increase voltage, counterclockwise to lower.

Tools: feeler gauge, crow foot wrench

1. Adjust valve clearance with engine at room temperature
2. Position piston at TDC of compression stroke (both valves closed), or set intake/exhaust valve fully open method
3. Loosen rocker arm jam nut; turn pivot ball stud while checking clearance with a feeler gauge
4. When clearance is correct, hold pivot ball stud and tighten rocker arm jam nut to specified torque with a crow foot wrench
5. Recheck valve clearance to make sure it did not change
6. Install rocker arm cover with a new gasket

Tools: AC frequency meter

1. Loosen governor clamp bolt
2. Hold governor lever at wide open throttle position
3. Rotate governor shaft counterclockwise (389/208/196cc) or clockwise (410cc) as far as it will go
4. Tighten governor lever clamp bolt to 110 in-lbs (389/208/196cc) or 70 in-lbs (410cc)
5. Turn speed adjustment screw counterclockwise three full turns to avoid overspeed
6. Start engine and let warm up under no-load
7. Connect AC frequency meter; no-load frequency should be 62.0-62.5 hertz
8. Turn speed adjust screw until frequency/RPM is within limits
9. Apply removable Loctite (Loctite 241) to speed adjust screw threads

⚠ Use a new rocker arm cover gasket.

Tools: feeler gauge, allen wrench, crow's foot

1. Adjust valve clearance with engine at room temperature.
2. Position piston at TDC of compression stroke (both valves closed).
3. Loosen the rocker arm jam nut.
4. Turn pivot ball stud while checking clearance with a feeler gauge.
5. Hold stud with allen wrench and tighten jam nut to specified torque with a crow's foot.
6. Recheck valve clearance after tightening.

⚠ Do not apply excessive torque to the governor shaft.

Tools: frequency meter

1. Loosen the governor lever clamp bolt.
2. Hold governor lever at full INC RPM; rotate governor shaft counterclockwise fully.
3. Tighten governor lever clamp bolt to 110 inch-pounds.
4. Turn speed adjustment screw counterclockwise three full turns.
5. Start engine and let it warm up and stabilize at no-load.
6. Connect frequency meter; set no-load frequency 62.0-62.5 hertz.
7. Add a drop of Loctite 241 to the speed adjust screw threads.

Tools: frequency meter

1. Loosen the governor clamp bolt.
2. Hold governor lever at wide open throttle; rotate governor shaft clockwise fully.
3. Tighten governor lever clamp bolt to 70 inch-pounds (8 Nm).
4. Start generator; let it stabilize and warm up at no-load.
5. Connect frequency meter across generator AC output leads.
6. Turn the primary adjust screw to obtain a frequency of 62.5 Hz.

Tools: non-metallic feeler gauge

1. Install or replace trigger pickup; ensure routing of wires is correct and not pinched.
2. With rotor in place, set gap to 0.20-0.30mm using the oval holes in the pickup bracket.
3. Align trigger point on rotor outside surface in-line with sensor and check/adjust gap with a non-metallic feeler gauge.
4. Tighten mounting screws to specification and check gap; adjust if necessary.

⚠ Hold the rocker arm jam nut in place as the pivot ball stud is turned.

Tools: Feeler gauge, 10mm Allen wrench (530cc engine), 13mm Allen wrench (410cc, 990cc, 999cc engines), Large socket and socket wrench

1. Engine should be cool before checking (60° to 80° F / 16° to 27° C).
2. Remove spark plug wires and position them away from the plugs; remove spark plugs.
3. Bring piston to Top Dead Center of its compression stroke (both valves closed).
4. Remove the four screws attaching the valve cover.
5. Loosen the rocker jam nut; turn the pivot ball stud while checking clearance with a feeler gauge.
6. Correct clearance is 0.002-0.004 inch (0.05-0.1 mm).
7. Hold the pivot ball stud and tighten the rocker arm jam nut to 174 in-lbs (19.68 N-m).
8. Recheck valve clearance to make sure it did not change.
9. Install new valve cover gasket and re-attach the valve cover.
10. Install spark plugs and re-attach the spark plug wire.
11. Repeat the process for the other cylinder, if necessary.

Tools: compression gauge

1. Remove spark plug.
2. Insert an automotive type compression gauge into spark plug hole.
3. Crank engine until there is no further increase in pressure; record highest reading.

Tools: Small engine tachometer or inductive tachometer

1. With engine running, connect engine tachometer per manufacturer instructions and record the engine RPM.
2. If engine rpm is within rated specs refer to flow chart; if outside range go to Problem 7 flowchart.

⚠ Explosion and Fire. Fuel and vapors are extremely flammable and explosive. Add fuel in a well ventilated area. Keep fire and spark away.

Tools: suitable fuel container

1. Open side panel to expose carburetor (A) and fuel pump (B).
2. Carefully remove fuel line from filter on inlet side of carburetor.
3. Using a suitable container, slowly pull on recoil cord and turn engine over; fuel should flow from fuel line.
4. If fuel does not flow, verify fuel is available to pump; inspect fuel filter and pulse line.
5. If fuel does not flow, replace fuel pump.