Yamaha Carburetor Bolt Set 6AU11 99999-04225-00. Overview. The Yamaha Carburetor Bolt Set 6AU11 99999-04225-00 is a genuine original equipment manufacturer kit designed to securely fasten carburetor components and maintain proper assembly integrity. This bolt set plays an essential role in keeping the carburetor properly sealed and aligned, helping ensure consistent fuel delivery and reliable engine performance.. Loose or worn hardware can lead to air leaks, fuel inefficiency, or unstable engine