Carburetor for Briggs & Stratton 594601 796587 591736, Fits 19HP 19.5HP 20HP 20.5HP 21HP Intek OHV Engine, Craftsman Riding Lawn Mower Tractor Single Cylinder Nikki Carb with Air Filter Kit

What It Is

This is a complete Nikki carburetor assembly with an air filter kit, designed to replace failed or clogged carburetors on single-cylinder Briggs & Stratton Intek OHV engines commonly used in Craftsman riding mowers and tractors. It’s a direct-fit replacement for the original carb, not a universal adapter.

Fitment & Compatibility

Before buying, verify:

• Engine model: Fits Briggs & Stratton Intek OHV single-cylinder engines with 19HP, 19.5HP, 20HP, 20.5HP, or 21HP ratings. Check your engine’s model number (e.g., 31C707, 33R877) on the valve cover or blower housing—this carb replaces OEM part numbers 594601, 796587, and 591736.
• Mower brand: Designed for Craftsman riding mowers/tractors, but also fits many Ariens, Husqvarna, Murray, and other brands using the same B&S Intek engine. Verify your mower’s deck size (42”, 46”, 50”, 54”) doesn’t block carb access.
• OEM vs aftermarket: This is an aftermarket part, not genuine Briggs & Stratton. It includes gaskets and an air filter, but the air filter element may differ slightly from OEM—measure your existing filter housing before installing.
• Physical check: Ensure the carb mounting flange matches your intake manifold (two-bolt pattern, 1.5” center spacing). The fuel inlet is 1/4” barb; confirm your fuel line size.

Key Things to Know

• Quality variance: Aftermarket Nikki clones can have casting flash or debris inside—clean the bowl and jets with carb cleaner before installing. Some units arrive with incorrect float settings; check float height (~1/8”).
• Installation difficulty: Moderate. You’ll need basic tools (screwdrivers, socket set) and patience to remove the old carb. Expect 30-60 minutes. Watch for stripped plastic intake manifold threads—use a torque wrench (max 100 in-lbs).
• Air filter fitment: The included filter may be slightly smaller than OEM. If it doesn’t seal, reuse your old filter or buy a genuine B&S air filter separately.
• Tuning required: After installation, you may need to adjust the idle mixture screw (turn 1.5 turns out from lightly seated) and check throttle linkage for full travel.

Should You Buy It

If your Craftsman or compatible riding mower has a failing B&S Intek carb (hard starting, surging, or fuel leaks), this is a budget-friendly fix—just expect to spend an extra 15 minutes cleaning and adjusting it. It’s not for those wanting a perfect OEM fit or zero tinkering, but for the price, it’s a solid repair option for a weekend mechanic.