Outdoor Power Equipment, Small Engine, Lawn Mower Repairs, Troubleshooting and Safety
Disassembly, Cleaning and Repair of Walbro LMK Carburetors used on Kohler Command and Courage Single Cylinder Engines
Kohler carb part numbers 12 053 01, 12 053 04, 12 053 06, 12 053 09, 12 053 10, 12 053 14, 12 053 15, 12 053 16, 12 053 18, 12 053 21, 12 053 22, 12 053 23, 12 053 25, 12 053 26, 12 053 27, 12 053 28, 12 053 29, 12 053 32, 12 053 34, 12 053 36, 12 053 39, 12 053 40, 12 053 43, 12 053 44, 12 053 45, 12 053 47, 12 053 49, 12 053 50, 12 053 51, 12 053 53, 12 053 55, 12 053 56, 12 053 57, 12 053 58, 12 053 59, 12 053 60, 12 053 61, 12 053 66, 12 053 68, 12 053 73, 12 053 74, 12 053 75, 12 053 76, 12 053 77, 12 053 78, 12 053 80, 12 053 81, 12 053 82, 12 053 83, 12 053 85, 12 053 91, 12 053 92, 12 053 93, 12 053 94, 12 053 95, 12 053 96, 12 053 98, 12 053 103, 12 053 104, 12 053 105, 12 053 107, 12 053 108, 12 053 109, 12 053 115, 12 053 116, 12 053 117, 12 053 118, 12 053 119, 12 053 130, 12 053 131, 12 053 132, 12 053 133, 12 053 135, 12 053 136, 12 053 139, 12 053 140, 12 053 145, 12 053 146, 12 053 147, 12 053 148, 12 053 149, 12 053 158, 12 053 159, 12 053 169, 12 053 177, 20 053 01, 20 053 02, 20 053 03, 20 053 04, 20 053 05, 20 053 06, 20 053 07, 20 053 14, 20 053 15, 20 053 16, 20 053 17, 20 053 18, 20 053 19, 20 053 20, 20 053 21, 20 053 22, 20 053 23, 20 053 42, 20 053 43, 20 053 44, 20 053 45, 42 053 01, 42 053 02, 42 053 03.
used on Kohler Engines CH5, CH6, CH11, CH12.5, CH13, CH14, CH15, CH16, CH410, CV11, CV12.5, CV13, CV14, CV15, CV16, CV430, CV460, CV461, CV462, CV463, CV464, CV465, CV490, CV491, CV492, CV493, CV494, CV495, SV470, SV480, SV530, SV540, SV590, SV600, SV610, SV620.
- Quick notes:
- The preset (preliminary adjustment) for the idle mixture needle valve is 1 turn out from lightly seated.
- The main jet is not adjustable.
- The low idle speed is typically 1200 rpm.
- The maximum high idle speed is typically 3750 rpm.
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- #1. LMK cast into carb body
The Walbro LMK carburetor can be identified by the letters 'LMK' cast into the carb body (#1).
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- #2. Kohler part number
The Kohler part number is stamped onto the carb body (#2, yellow).
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- #3. Walbro LMK carb with anti-afterfire solenoid
The Walbro LMK carburetor may be equipped with an anti-afterfire solenoid (#3, yellow) in place of the fuel bowl retaining screw. It also may have an idle adjustment limiter cap (#3, green). The green wire provides an electrical ground for the solenoid.
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- #4. Anti-afterfire solenoid
When the engine is shut down the spark is disabled and the engine coasts to a stop. While the engine is coasting, fuel is still being drawn in from the carb, and the unburned fuel continues out to the hot muffler where it may explode loudly. The anti-afterfire solenoid (#4) stops fuel flow into the engine as soon as the keyswitch is turned off. The plunger or pintle is extended by a spring and retracts when supplied with 12 volts positive at the wire terminal and the casing is grounded.
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- #5. Fixed main jet
The main jet is pressed into the side of the center pedestal (#5). Its removal is not recommended or necessary unless a high-altitude jet is being installed.
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- #6. Emulsion tube, idle fuel pickup
The main fuel emulsion tube and the pickup tube for the idle circuit are pressed into place and removal should not be attempted (#6).
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- #7. Removal of float hinge rod
The float should rest parallel to the carb body when inverted. The float height is not adjustable. The float hinge rod slides out either side (#7) and the float with inlet needle can be lifted out.
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- #8. Inlet valve needle
When the fuel in the fuel bowl rises, the float pushes the needle against the inlet seat slowing fuel flow. Inspect the inlet needle for corrosion and damage or wear to the rubber tip (#8). The inlet valve seat is pressed into place and removal is not recommended.
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- #9. Idle fuel tube, air bleed, choke stop pin
The choke plate is prevented from going past wide open by a stop pin (#9, red). An idle air bleed hole is shown at #9, blue. There is another hole directly opposite the one seen. On some variations a hole may be drilled at #9, green to supply air into the idle fuel.
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- #10. Welch plug removal
The welch plug that covers the idle fuel mixing well can be removed to facilitate cleaning the idle progression holes (#10). Use a sharpened punch to pierce the plug and pry it out.
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- #11. Idle fuel mixing well
Fuel from the idle fuel pickup tube arrives at the mixing well through the passage at the top right (#11). The two small holes supply fuel into the carb bore when the throttle is open slightly, i.e. at low idle. Fuel also continues out the lower passage to the idle mixture adjustment needle.
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- #12. Idle fuel discharge holes
The two small holes that were seen in the idle mixing well lead directly into the carb bore (#12, yellow) supplying fuel while the throttle plate is near the closed position for a smooth transition from low to high idle.
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- #13. Primary idle fuel port
The primary idle fuel discharge port is located beyond the throttle plate (#13). The amount of fuel delivered is metered by the idle adjustment valve. The preliminary setting for the needle is one turn out from lightly seated. With the engine warmed up and running at 1200 rpm, 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.
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- #14. Idle speed screw
The idle speed screw limits how far the throttle plate may close go, thereby setting idle speed (#14). Low idle speed is typically 1200 rpm.
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- #15. Main air bleed
The main air bleed is located just prior to the venturi (#15, yellow). It supplies air to the emulsion tube to atomize fuel being drawn into the venturi from the nozzle.
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- #16. Choke plate, plastic choke shaft
If the choke shaft is plastic, the choke plate can be pulled out with pliers (#16).
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- #17. Self-relieving choke
The choke shaft of the self-relieving choke is off-center and spring loaded (#17). When vacuum at the choke is high enough it overcomes the spring and relieves the choke.
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- #18. Choke relief spring
The choke relief spring is assembled with the lower tang end at the second notch from the right as shown (#18).
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- #19. Choke shaft bushing
The choke shaft bushing can be removed with a screw extractor (#19). When installing a new bushing use a 3/16 in. drill blank as an alignment tool.