Fixing Persistent Carb Leaks Pressure Testing & Reseating Needle Valves on a Zephyr 1100

Leaking carburetors can drive you mad — especially when they still leak after cleaning, rebuilding, and fitting new parts. In this video, I’m working on a Kawasaki Zephyr 1100 that continued to leak fuel even after new diaphragms, floats, and jets were installed. The garage smelled like a petrol factory, and I was determined to finally get to the bottom of it. I show how I bench-tested the carburetors using a petrol carburetor pressure diagnostic tool, identified exactly which carb was leaking, and fixed the issue by reseating the needle valves using a careful polishing process. This is a method you can use when normal cleaning and rebuilding just isn’t enough. The video also covers: Bench pressure testing motorcycle carburetors Identifying leaking needle valves Polishing needle valve seats using fine valve grinding paste Why rebuilt carbs can still leak A useful screw-removal tool for damaged carb bowl screws If you’re restoring or maintaining an older motorcycle and struggling with persistent carb leaks, this process can save you a huge amount of time — and prevent pulling the carbs off again. The fuel tap on the tank is also leaking, so rebuilding that properly will be covered in the next video. 👍 If this helps, consider subscribing for more real-world motorcycle repair and restoration content.