I recently picked-up a smallish Bultaco...a Campera, which came equipped with a very old Amal. This fifty year old device just did no do this bike justice. At first I was not sure if the problem was with the ignition of the carburetor. Since the carburetor was obviously well past its prime, I opted to look for an oriental replacement. Enter the Chinese Mikuni.

Attaching this carburetor to the Bultaco was relatively simple...once you figure out where to get the pieces. It transforms the motorcycle. It now idles, accelerates without hesitation, and runs cleanly at all speeds. However, it is reluctant to start...either when it's cold or hot, so I still have some work to do.

A much fuller description higher resolution pictures, and links to suppliers are on my blog.

Feel free to take a look

Mike

meditativemachinery

back in the day a Mikuni conversion (usually from sammy miller) was a common (big) improvement.

+1

and to be honest even "newer" Bultaco models run better with most Mikuni or DellOrto mounted.

The design of the older Amal and Bing carburators was not very effective ...