Carburetor For 42 in Troy bilt pony 13AN77TG766 13AJ609G766 13AN77KG066 Bronco Riding Lawn Mower Compatible with Briggs Stratton 15.5HP 17.5HP 500cc Engines Carb

What It Is

This is an aftermarket carburetor designed to replace the OEM unit on 42-inch Troy-Bilt Pony and Bronco riding mowers powered by Briggs & Stratton 15.5HP or 17.5HP 500cc engines. It meters fuel and air into the engine for combustion—if your mower won’t start, runs rough, or stalls under load, a clogged or failed carb is often the culprit.

Fitment & Compatibility

Before buying, confirm these three things:

• Model numbers: This carb fits Troy-Bilt Pony models 13AN77TG766, 13AJ609G766, and 13AN77KG066, plus Bronco models with 42-inch decks. Check your mower’s model plate (under the seat or on the frame) for an exact match.
• Engine: Works with Briggs & Stratton 15.5HP (Model 31C707) and 17.5HP (Model 31C707 or 31P977) 500cc single-cylinder engines. Verify your engine model number (stamped on the valve cover or blower housing).
• Physical fit: The carburetor mounting flange and bowl dimensions match OEM Briggs 594257 and 698369. Measure the distance between mounting bolt holes (approx. 2.5 inches center-to-center) and the intake port diameter (approx. 1 inch) to be sure.

It is an aftermarket part—not OEM—so gaskets and seals may vary slightly. Some users report needing to swap the old float or needle with the original if the new one doesn’t seat perfectly.

Key Things to Know

• Installation difficulty: Moderate. Expect to remove the air filter housing, fuel line, and throttle/governor linkage. Have a small screwdriver set and needle-nose pliers handy. A new fuel filter is recommended.
• Quality variance: Aftermarket carburetors are hit-or-miss. This one rates 4.7/5 but only has 6 reviews. Check for debris inside the bowl before installing—flush it with carb cleaner.
• Common gotcha: The included gaskets may be too thick or thin. Reuse your OEM gasket if the new one causes a vacuum leak. Also, the throttle linkage hole might need slight filing to fit your cable.
• Tuning: After installation, you may need to adjust the idle mixture screw (usually 1.5 turns out from lightly seated) and the idle speed screw. A tachometer helps, but ear-tuning works.

Should You Buy It

If your Troy-Bilt Pony or Bronco with a 15.5–17.5HP Briggs engine is surging, hard-starting, or won’t run, this is a budget-friendly fix—just be prepared for minor fit adjustments. It’s not plug-and-play like an OEM unit, but at ~$25, it’s worth the gamble if you’re comfortable with basic carb work. Skip it if you want guaranteed zero-hassle installation or have a different engine model.