Yamaha - Carburetor(lower) - 6K5-14303-03-00Yamaha Carburetor Lower Assembly Fuel Delivery Component 6K5 14303 03 00 Overview The Yamaha Carburetor Lower Assembly 6K5 14303 03 00 is one of those parts that can quietly throw everything off when it starts to wear out. If your engines been idling rough or not responding cleanly on throttle, this lower section of the carb is often where the issue sits. It handles fuel flow and sealing inside the carb body, so everything has to stay tight and clean.