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Kohler CV14S Carburetor

Kohler CV14S carburetor adjustments should be made only after the engine has warmed up. These engines are equipped with one of two basic types of fixed main jet carburetors: Walbro or Nikki.

Walbro carburetors have a low idle speed screw and a low idle fuel adjusting needle. Nikki carburetors only have a low idle speed screw. Certified carburetors will have fixed idle fuel or a limiter cap on the idle fuel adjusting needle.

The carburetor is designed to deliver the correct fuel-to-air mixture to the engine under all operating conditions. The main fuel jet is calibrated at the factory and is not adjustable. The low idle fuel adjusting needle is also set at the factory and normally does not need adjustment.

To ensure correct engine operation at altitudes above 1525 meters (5000 ft.), it may be necessary to install a special high-altitude jet kit in the carburetor. If a high-altitude kit has been installed, the engine must be reconverted to the original jet size, before it is operated at lower altitudes, or overheating and engine damage can result.

Kohler CV14S Carburetor Troubleshooting

If engine troubles are experienced that appear to be fuel system related, check the following areas before adjusting the carburetor. Make sure the fuel tank is filled with clean, fresh gasoline. Make sure the fuel tank cap vent is not blocked and that it is operating properly.

If the fuel tank is equipped with a shut-off valve, make sure it is open. If the engine is equipped with an in-line fuel filter, make sure it is clean and unobstructed. Replace the filter if necessary. Make sure fuel is reaching the carburetor. This includes checking the fuel lines and fuel pump for restrictions or faulty components, replace as necessary. Make sure the air cleaner element is clean and all air cleaner element components are fastened securely.

If, after checking the items listed above, the engine is hard to start, runs roughly, or stalls at low idle speed, it may be necessary to adjust or service the carburetor.

Kohler CV14S Carburetor Adjustment

Engines may have a fixed idle or limiter cap on the idle fuel adjusting needle. Step 2 can only be performed within the limits allowed by the cap.

1) Start the engine and run at half throttle for 5 to 10 minutes to warm up. The engine must be warm before doing steps 2 and 3.

2) Low Idle Fuel Needle Setting (Walbro Carburetor): Place the throttle into the idle or slow position. Turn the low idle fuel adjusting needle out (counterclockwise) from the preliminary setting until engine speed decreases (rich). Note the position of the needle. Now turn the adjusting needle in (clockwise). The engine speed may increase, then it will decrease as the needle is turned in (lean). Note the position of the needle. Set the adjusting needle midway between the rich and lean settings.

3) Low Idle Speed Setting (Walbro and Nikki Carburetor): Place the throttle control into the idle or slow position. Set the low idle speed to 1200 RPM (± 75 RPM) by turning the low idle speed adjusting screw in or out. Check the speed using a tachometer.

The actual low idle speed depends on the application – refer to equipment manufacturer’s recommendations. The recommended low idle speed for basic engines is 1200 RPM. To ensure best results when setting the low idle fuel needle, the low idle speed must not exceed 1200 RPM (± 75 RPM).

When troubles occur, be sure to check the simple causes which, at first, may seem too obvious to be considered. For example, a starting problem could be caused by an empty fuel tank. Some common causes of engine troubles are listed in the following table. Do not attempt to service or replace major engine components, or any items that require special timing or adjustment procedures.