Koubliztic Carburetor for Bolens 21-inch 140cc Lawn Mower Kit — Fits B&S 300E–550EX, Primer & Air Filter

High-quality replacement carburetor kit for Bolens 21" 140cc mowers that restores fuel flow and fit for models using B&S 300E–550EX series engines.

If your Bolens, MTD or Murray 21" mower with a 125–140cc Briggs & Stratton style engine is running rough, hard to start, or not idling properly, replacing the carburetor often fixes the issue. This complete Koubliztic kit includes the carburetor plus common consumables so you can reassemble and test without extra trips to the parts store. It’s engineered to align with the factory mounting points and fuel connections for models listed under part numbers such as 799583 and several OEM reference codes.

How will this carburetor improve mower starting and idling?

Swapping in a fresh carburetor removes clogged passages and worn jets that cause poor cold and hot starts. The calibrated fuel delivery and integrated primer bulb make choke and starting behavior more consistent, reducing stalls and rough idling.

• Direct-fit for specific 140cc B&S-style engines listed in the compatibility set
• Includes primer bulb and fuel shutoff for cleaner starts and safer storage
• Rebuilt fuel passages to restore steady idle and throttle response

Will this fit my mower model and which part numbers does it replace?

This cartridge was designed to replace carburetor assemblies used on Bolens 21" mowers with 125–140cc engines and matches OEM references. It replaces several factory part numbers, so cross-checking your current part number or engine code ensures a hassle-free installation.

• Replaces 799583 and other common OEM numbers like 593261 and 595656
• Compatible with codes such as 08P502-0034-F1 through 09P702-0128-F1 listed in the compatibility data
• Designed to match bolt pattern and fuel line locations for models 11A-B0BL765 and 11A-020W765

What comes in the box and what tools will I need?

The kit supplies the parts you typically replace when refreshing a carburetor installation, so you won’t need to source extra small components. Basic hand tools and a clean workspace are all that’s required to complete the swap in most cases.

• Includes carburetor (799583), spark plug, two air filters, and air filter cover
• Also supplied: primer bulb, fuel filter, fuel shutoff valve, fuel hoses, clamps, and rings
• Simple installation with screwdrivers, pliers, and a socket set; no specialized tools required

How durable is this replacement part and what maintenance is recommended?

The assembly is built from durable materials intended for routine mowing conditions; consumables like the air filter and fuel filter are included to prolong service life. Regular cleaning of the air filter and using fresh gasoline will help maintain performance and extend service intervals.

• Robust construction to stand up to regular lawn care use
• Replace the air and fuel filters seasonally or sooner if used in dusty conditions
• Use clean, stabilized fuel and follow manufacturer torque guidelines when installing

Who this is for: This Koubliztic carburetor kit is ideal for homeowners, landscapers and DIY mechanics who own a Bolens, MTD or Murray 21" lawn mower with a 125–140cc Briggs & Stratton-style engine and need a direct replacement. Choose this kit if you want a complete parts set—carburetor, filters, primer and fittings—to restore reliable starting and throttle response without sourcing multiple components separately.