Carburetor Carb Kit For Ryobi 4 Cycle S430 WeedEater Lawn mower Replace 20016-81020 20016-81021 with fuel line kit

What It Is

This is an aftermarket carburetor kit for Ryobi 4-cycle S430 WeedEater trimmers and similar handheld lawn equipment. It includes the carburetor, gaskets, fuel lines, and filters needed to replace a worn or clogged fuel system.

Fitment & Compatibility

• Direct fit for: Ryobi 4-cycle S430 WeedEater models (e.g., RY4S30, 790R).
• OEM numbers: Replaces Ryobi part numbers 20016-81020 and 20016-81021.
• Check before buying:
  • Verify your machine’s model number (look on the engine shroud or under the primer bulb).
  • Confirm the carburetor mounting hole spacing (typically 40mm center-to-center on S430).
  • Ensure the fuel line kit matches your tank size (this kit includes 3/32” and 1/8” lines common for S430).
• Not compatible with: 2-cycle trimmers, larger Ryobi mowers, or non-Ryobi brands without adapter modifications.

Key Things to Know

• Quality is mixed: Some users report the carb works fine out of the box; others need to clean it or replace gaskets to fix vacuum leaks.
• Installation difficulty: Moderate. You’ll need to remove the air filter housing, old carb, and fuel lines. A small screwdriver set and needle-nose pliers help.
• Common gotcha: The included fuel line may be slightly too long or stiff—trim to match original length and soak in gas for 10 minutes to soften before installation.
• Tuning required: After install, you may need to adjust the idle screw (turn clockwise to raise idle) if the engine stalls or runs rough.

Should You Buy It

If your Ryobi S430 WeedEater won’t start, idles poorly, or leaks fuel, this kit is a cheap fix—just be prepared for minor adjustments or quality checks. It’s a good value for DIYers who don’t want to pay $40+ for an OEM carb, but skip it if you want guaranteed plug-and-play reliability.