These JRC Carburetors are 26mm, and are a great alternative to Amal 626 carburetors for your vintage British motorcycle. These are a direct bolt on replacement for your stock Amal, and will use your stock throttle cable. These feature a chrome slide for smoother operation and less wear, as well as an integrated choke lever on the body of the carburetor for easy starting. These are also known as PWK or Keihin carburetors, they are adapted for use on British and Japanese motorcycles by JRC Engineering. These 26mm carbs are supplied with P26-115 main jets, which is like an Amal 160 main. The pilot jet is a #38.
These carburetors have been used on such motorcycles as 500 c.c. Triumphs, 3-cylinder Triumph Trident, 200 c.c. Triumph Tiger Cub single-cylinder, 250 c.c. BSA, and 175 cc Hondas with great success, they are highly adaptable to many motorcycle makes and models.
You can find installation instructions and a parts list for JRC Flatside Carburetors here