Carburetor for 300E 450E 500E 550EX 500 125cc 140cc 08P502 8P502 09P602 9P602 Lawn Mower Engine Replace OE # 799583

What It Is

This is a replacement carburetor for small, single-cylinder lawn mower engines in the 125cc to 140cc range, commonly found on 300E, 450E, 500E, 550EX, and similar push mowers. It meters fuel and air into the engine for combustion; if your mower won’t start, runs rough, or stalls, a clogged or failed carb is often the culprit.

Fitment & Compatibility

Before buying, confirm your engine’s model number—not the mower deck size. This carburetor fits engines with model numbers 08P502, 8P502, 09P602, or 9P602 (e.g., Briggs & Stratton 500E series). It replaces OEM part #799583. Measure the mounting bolt spacing (typically 2.75 inches center-to-center) and check that the fuel line inlet diameter matches your existing hose (usually 1/4 inch). If your engine uses a primer bulb, verify the carb has the correct port. This is an aftermarket part, not genuine Briggs & Stratton, so minor fitment adjustments (e.g., gasket trimming) may be needed.

Key Things to Buy

• Quality is decent for the price – buyers report it works well out of the box, but some units may need a quick cleaning of internal jets due to manufacturing debris.
• Installation is moderate – you’ll need a screwdriver, pliers, and possibly a small socket set. Expect 20–40 minutes; label fuel lines and throttle linkage before removal.
• Common gotchas – the gasket included can be thin; consider using a thin layer of gasket sealant. Also, the choke linkage may need slight bending to align perfectly with your engine’s lever.
• Adjust the idle mixture screw – if the mower runs lean or rich after install, turn the screw (if present) 1.5 turns out from fully seated as a starting point.

Should You Buy It

If your engine matches the model numbers listed and you’re comfortable with basic small-engine repair, this is a budget-friendly fix for a non-starting or rough-running mower. It’s not a long-term OEM replacement, but for $12.99 it often restores function for a season or two—ideal for older mowers not worth a costly genuine part.