Lawn Mower Carburetor for 300E 450E 500E 550EX 08P502 09P602 125CC 140CC Carburetor Replacement 799583 593261 591979 591160 590556

What It Is

This is an aftermarket carburetor designed to replace the OEM units on a range of small-engine lawn mowers, specifically for 125cc and 140cc engines used in 300E, 450E, 500E, and 550EX models. It’s a direct swap for the fuel delivery system, mixing air and fuel for combustion.

Fitment & Compatibility

• Engine families: Fits 125cc and 140cc engines from brands like Craftsman, Troy-Bilt, MTD, and Cub Cadet—commonly found on push mowers with 21-inch or 22-inch decks.
• OEM part numbers: Cross-references with 799583, 593261, 591979, 591160, and 590556. Verify your old part number matches one of these.
• Model check: Works with 08P502 and 09P602 engine series. Look for a model tag on the engine shroud (e.g., 125C or 140C).
• Physical fit: Measure the mounting flange bolt spacing (typically 2.5 inches center-to-center) and the intake/outlet diameter. This is a standard small-engine carb, but aftermarket builds can vary slightly.
• Gaskets: Usually includes a gasket kit, but check if your intake manifold gasket is compatible (some engines use a separate O-ring or paper gasket).

Key Things to Know

• Quality variance: At this price, expect basic construction. Some units may have rough casting or minor debris in fuel ports—rinse with carb cleaner before installing.
• Installation difficulty: Easy for DIYers with basic tools (socket set, screwdriver). Requires removing the air filter housing, fuel line, and throttle linkage. No special tuning needed—most are preset, but you may need to adjust the idle screw.
• Common gotchas: The throttle linkage arm may not align perfectly with your mower’s cable. You might need to re-bend or swap the arm from your old carb. Also, the fuel line barb can be slightly larger—use a hose clamp if it’s loose.
• Prime and start: After install, prime the carb (if equipped) or pour a teaspoon of fuel into the bowl vent to help it start. Crank for 10-15 seconds; if it doesn’t fire, check for a stuck float or debris in the jet.

Should You Buy It

This is a budget-friendly fix for a non-running mower with a dead carburetor. It’s ideal if you’re handy and don’t mind minor adjustments. For occasional use on a single mower, it’s a solid value. If you need a perfect OEM fit or run a commercial operation, spend more on a genuine replacement.