799579 Air Filter Tune Up Service Kit for B&S 550E 500E 550EX 300E 450E 55EX 08P502 09P602 09P702 Overhead Valve Engines Lawn Mower with 594281 Primer Bulb 491055 491055S RC12YC Spark Plug

What It Is

The 799579 Air Filter Tune Up Service Kit bundles the essential maintenance parts for B&S 550E, 500E, 550EX, 300E, 450E, 55EX, and 08P502/09P602/09P702 overhead valve engines. It includes an air filter, fuel filter, spark plug (RC12YC), and primer bulb (594281/491055) for a single-service refresh on push mowers, riders, or pressure washers using those engines.

Fitment & Compatibility

• Engine models: Confirm your engine model number (stamped on valve cover or shroud) matches B&S 550E, 500E, 550EX, 300E, 450E, 55EX, 08P502, 09P602, or 09P702. Not for side-valve or older flathead engines.
• Deck size irrelevant: Fitment depends on engine, not mower deck width. Works across brands (Troy-Bilt, Craftsman, etc.) using those B&S engines.
• OEM vs aftermarket: This is an aftermarket kit. OEM numbers: 799579 (air filter), 594281 (primer bulb), 491055/491055S (fuel filter), RC12YC (spark plug). Measure primer bulb stem diameter (~0.5 in) to verify fit.
• Check primer bulb: If your engine uses a different bulb shape (e.g., square or push-button), this round bulb may not match. Compare old bulb to included one before installing.

Key Things to Know

• Installation difficulty: Easy (15–20 minutes). No special tools beyond a socket for the spark plug and pliers for the fuel line.
• Spark plug gap: The RC12YC plug comes pre-gapped, but verify at 0.030 in (0.76 mm) for best performance. Adjust if needed.
• Fuel filter orientation: Arrow on filter must point toward engine (fuel pump/carb). Reverse will starve fuel.
• Primer bulb durability: Aftermarket bulbs may be slightly softer than OEM; avoid over-priming (3–5 presses max) to prevent cracking.

Should You Buy It

Yes, if you have a compatible B&S overhead valve engine and want a complete, low-cost tune-up in one box. It’s ideal for DIY maintenance—saves hunting individual parts. Skip it if you need OEM-specific fit for a non-standard primer bulb or prefer exact OEM tolerance for commercial use. For $8, it’s a solid value for home mowers.