If you are looking to replace the OEM diaphragm carburetor on your 1980 Kawasaki KZ250 Ltd. with a slide carburetor to address the lean running issue, there are a few options to consider. It's important to note that carburetor compatibility can vary based on factors such as engine size, mounting points, and intake manifold design. Here are a couple of popular slide carburetor options you can explore:
Mikuni VM Series Carburetors: Mikuni VM carburetors are widely used and known for their performance and adjustability. For a 250cc engine like yours, a Mikuni VM26 carburetor is often a popular choice. It features a 26mm bore size, which can provide improved fuel delivery and tuning options compared to the OEM diaphragm carburetor.
Keihin PWK Series Carburetors: Keihin PWK carburetors are also highly regarded in the motorcycle community. The PWK series offers excellent performance and tunability. For a 250cc engine, a Keihin PWK28 carburetor could be a suitable choice. It has a 28mm bore size and can provide increased fuel flow and adjustability.
When selecting a slide carburetor, it's crucial to ensure that it fits your intake manifold and throttle cable arrangement. You may need to check for compatibility or make necessary modifications to ensure proper fitment.
Additionally, after installing a new carburetor, you will need to rejet and tune it to match the increased airflow from the K&N filter. This involves selecting the appropriate jet sizes for the main, pilot, and needle jets, as well as adjusting the air-fuel mixture screw and idle speed to achieve proper fueling and performance.
It's recommended to consult with experienced motorcycle technicians or enthusiasts who have knowledge of your specific motorcycle model and can provide guidance on carburetor selection, installation, and tuning procedures.