A-B1844987-AI KIT-IDLE MIXTUREOne New Aftermarket Replacement Idle Mixture Kit Fits Briggs and Stratton Small Engines This carburetor idle mixture kit replaces the idle mixture screw, spring, and related components inside the carburetor of Fits Briggs and Stratton (B&S) small engines. The idle mixture assembly controls the air fuel ratio at idle and low speed throttle positions, and is a key component during carburetor rebuilds or when correcting rough idle, stumbling, or poor low