Since this thread is about Chinese carburettors, I thought I should mention my seven C3M carbs. One is an original Japanese Zama, two are Chinese Zamas off of 365s and 4 are Chinese copies of Chinese Zamas.
The Japanese Zama is off a 044 and is essentially a Walbro, it has the same simple jetting configuration of the Walbro. The other six Chinese C3Ms use the 'twin jet' metering system. The twin jet carbs are easy to set up as each function; idle, transition, max low speed circuit flow and high speed circuit flow, can be adjusted separately. The carbs allow you to dial in the carburetion with a minimum of compromise.
The only Zama of the seven carbs that I am not going to use is the original Japanese Zama. I am stripping the hardware off the carb to put on one of the Chinese twin jet carbs. That carb will be going on a project 029 of mine.
The four Chinese copies of the Chinese Zamas work the same as the Zamas. The only significant difference was that they came with too long a discharge nozzle and the pump diaphragm was a bit thicker. I didn't notice any difference in the operation of the carb with the slightly thicker diaphragm. I have repositioned the discharge nozzles so that they are only just appearing in the venturi.
I was given the four Chinese copies, but they are available cheaply off the internet for around $20. With a micro drill set and a pin vise, you can convert one of these cheap Chinese copies into a better performing carb than the one that came from the factory.
I think the Zama carbs got a bad name because they could be dialled in by the factory to please the EPA. However, just as it is easy to modify the carbs in to run on fumes, it is also easy to modify the carbs to pump some serious hydrocarbons.
I find it ironic that of the seven carbs, the only one I'm not going to use is the original Japanese one.
