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Kohler CV15S Carburetor

Kohler CV15S - Walbro Carburetor Adjustment

Kohler CV15S engines are equipped with fixed main jet Walbro carburetors. Walbro carburetors have a low idle speed screw and a low idle fuel adjusting needle.

Carburetor adjustments should be made only after the engine has warmed up. 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 idle fuel adjusting needle is also set at the factory and normally does not need adjustment. Engines operating at altitudes above approximately 1830 m (6000 ft.) may require a special high altitude main jet. If, however, the engine is hard-starting or does not operate properly, it may be necessary to adjust or service the carburetor.

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 step 2.

2) Low Idle Fuel Needle Setting: 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.

Kohler CV15S - Walbro Carburetor Disassembly

Remove the bowl retaining screw, retaining screw gasket, and fuel bowl. Remove the bowl gasket, float shaft, float, and fuel inlet needle. Remove the low idle speed screw and spring. If there is a low fuel adjusting needle without a limiter cap, remove the needle and spring.

Do not attempt to remove the needle if it has a limiter cap. Further disassembly to remove the welch plugs, main fuel jet, fuel inlet seat, throttle plate and shaft, and choke plate and shaft is recommended only if these parts are to be cleaned or replaced.

Welch Plug Removal

- In order to clean the idle ports and bowl vent thoroughly, remove the welch plugs covering these areas.
- Use Tool and the following procedure to remove the welch plugs.
- Pierce the welch plug with the tip of the tool.
- To prevent damage to the carburetor, do not allow the tool to strike the carburetor body.
- Pry out the welch plug with the tip of the tool.

Main Fuel Jet Removal

The main jet on Walbro carburetors is pressed into the side of the tower portion of the body. Removal is not recommended, unless a high-altitude kit is being installed, in which case the removal instructions will be included in the kit.

Fuel Inlet Seat Removal

The fuel inlet seat is pressed into the carburetor body, do not attempt to remove it. If necessary, clean it in place with aerosol carburetor cleaner.

Choke Shaft Removal (Non-Self-Relieving)

Because the edges of the choke plate are beveled, mark the choke plate and carburetor body to ensure correct reassembly. Also take note of the choke plate position in bore, and the position of the choke lever and choke return spring.

Some carburetors have the choke plate inserted into a slot in the choke shaft. Grasp the choke plate with a pliers and pull it out of the slot. Other carburetors will have the choke plate fastened to the shaft with screws. Carefully remove the screws and separate the plate from the shaft. Use a fine-toothed file to remove any burrs from the shaft. Remove the choke shaft and choke return spring.

Throttle Shaft Removal

Do not attempt to remove the throttle shaft, as repair kits are not available. Throttle shaft wear is normally accompanied by corresponding wear to the carburetor body, making it impractical to attempt a cost-effective repair. Replace the entire carburetor if the throttle shaft is worn.

Kohler CV15S - Walbro Carburetor Inspection

- Carefully inspect all components and replace those that are worn or damaged.
- Inspect the carburetor body for cracks, holes, and other wear or damage.
- Inspect the float for cracks, holes, and missing or damaged float tabs.
- Check the float hinge and pin for wear or damage.
- Inspect the fuel inlet needle and seat for wear or damage.
- Inspect the tip of the low idle fuel adjusting needle for wear or grooves.
- Inspect the throttle and choke shaft and plate assemblies for wear or excessive play.

Kohler CV15S - Walbro Carburetor Reassembly

Choke Shaft Installation (Non-Self-Relieving)

- Install the choke return spring to the choke shaft.
- Insert the choke shaft with return spring into the carburetor body.
- Rotate the choke lever approximately 1/2 turn counterclockwise.
- Make sure the choke return spring hooks on the carburetor body.
- Position the choke plate as marked during disassembly.
- Insert the choke plate into the slot in the choke shaft.
- Make sure the choke shaft is locked between the tabs on the choke plate.
- If the choke plate was attached with screws, loosely attach the plate to the shaft.
- Close the choke and center the choke plate in the bore.
- Tighten, but do not over-tighten the screws.
- Check that the choke moves freely and that the plate does not bind in the bore.

Welch Plug Installation

- Position the carburetor body with the welch plug cavities to the top.
- Place a new welch plug into the cavity with the raised surface up.
- Use the end of the tool that is about the same size as the plug and flatten the plug.
- Do not force the plug below the surface of the cavity.
- After the plugs are installed, seal them with Glyptal (or an equivalent sealant). Allow the sealant to dry.
- If a commercial sealant is not available, fingernail polish can be used.

High Altitude Operation

When operating the engine at altitudes of 1830 m (6000 ft.) and above, the main fuel mixture tends to get overrich. An overrich mixture can cause conditions such as black, sooty exhaust smoke, misfiring, loss of speed and power, poor fuel economy, and poor or slow governor response.

To compensate for the effects of high altitude, a special high altitude main fuel jet can be installed. High altitude jets are sold in kits which include the jet and necessary gaskets. Refer to the Parts Manual for the engine being serviced for the correct kit number.